Ok, here is what I would propose:
I am about to detail a comprehensive training plan, and give you the reasonings behind it. I appreciate your comment about committing to it 100% for 1 month, but I'm going to ask you to commit to it 100% for 12 weeks as an initial cycle. I am optimistic that you will be encouraged by the training program and my explanations, and I hope you will not see this as an imposition, rather an opportunity. There are a number of reasons for this:
1. I expect you to be able to make linear progress for at least the next 12 weeks
2. Given your starting point, it will take you longer than four weeks to ingrain the changes you need to make to set yourself up for future success. After 1 month, it is all too easy to program hop, find excuses, etc.
3. I am serious about trying to help you, and I do not feel it is a particular commitment on my part to offer you some online help over the course of a month. A longer investment by me in your success is likely to reap greater results for you. As your progress will be the only reward I recoup from this, I would like it to be worthwhile.
I'm going to cover principles first, and then give you a template for diet and food at the end. Please do not skip the principles part, as anyone who has experienced any kind of success will tell you that principles count for far more than templates or routines.
A Diet
The first thing to start with is diet. There is a lot of room for improvement, and a commitment to the training plan is worth very little without a commitment to a diet plan. If cooking is not your forte, I will help you by trying to give you easy, tasty recipes and affordable food choices. You should feel free to ask me any questions you like on this.
The first diet mandate is that I want you to get used to eating 3 meals per day. I don't mind how you spread them out. For the first week or two, I don't actually mind whether you increase your calorie intake or just spread out your existing intake through the day, the important thing in the first instance is to ingrain the mentality that eating supports your performance/appearance goals.
The second mandate will be to gradually improve the food choices you are making. There is only one instance of meat and veg in your daily diet. That will not be enough to support support appreciable progress. Without wanting to be overly harsh, you need to get in the mindset that if you want to look and perform like a badass, you need to start eating like one. Your diet currently is childish. We cannot accept that as an unshakable reality if we want to make progress. You must commit to improving the way in which you fuel your body, even if you only start by adding an apple once a day. This mandate is one of the reasons I want you to commit to at least 12 weeks - there is too much work to be done, and the changes would be unsustainabe if we tried to make them all at once.
The third diet mandate is that once you are comfortable eating three meals per day, I want you to try to increase the amount of food you eat over your three meal period. It can be as easy as adding another glass of milk, or another slice of meat, or even a spoonful more rice, and it doesn't have to be to every single meal (initially). You are seriously undereating, and it is the reason your lifts are not what they could be.
The fourth mandate, to help you put it all together, is I want you to journal what you eat. It can be here, or on paper, but I'd like you to write it down, and share it with me at the end of each week. Accountability, to yourself and to someone who is doing your programming, is the most effective way to push yourself to make progress. I would like you, when you are writing down your day's food, to be looking at it and comparing it to the day, or week before, and competing with yourself to make progress by consistently, incrementally improving, both the quality and quantity of what you're eating.
Tip - cook meals in advance, or make a lot of something and just reheat it for another meal. If you can make spaghetti, make enough for 5 portions, for example.
B Training
Again, your routine can be dramatically improved upon. We're going to throw it out completely, so I won't dwell on details, but your chest is essentially the only thing being worked, and even that is less effective than it could be.
The philosophy of your routine, from previous posts, is going to be to make you a stronger, tougher, fitter individual. In prioritising strength, fitness, and toughness, we will need to make room for exercises that play a support role to those goals, building the surrounding musculature and making you resilient to injury.
One of the reasons I want you to commit to 12 weeks is that we need to phase your training. The first month will be about establishing habits, assessing your current level and ability to recover, and ingraining belief in this method of training. The second month will see you mainly trying to build on the strength aspect of this, and in the third month, we'll look to push more on the conditioning as well. Every day, of every week, for 12 weeks, we will be trying to end each day as a better athlete than we started it.
To get down to the actual philosophy of the routine itself, here is how we are going to structure your training:
You've said you'll go to the gym 3x per week. I'd prefer it to be four, but three is plenty to make progress, and we will work with that initially.
Each gym workout will be based around a primary movement. As someone who is not a competitive strength athlete, your aim in this movement is to get stronger, rather than to get better at performing the movement itself. This movement will be the first thing we do at the gym, and will be our primary measure of progress for the first 12 weeks. This movement will always be free weight-based. Machines are for assistance, never for primary movements.
We will then perform one or two assistance exercises, aimed at either inducing further hypertrophy in the muscles involved in the first movement, or in the antagonist/supportive musculature. We will also add in one exercise where the primary purpose is maintaining health/resistance to injury. I prefer to do one after the other in a giant set, and rest after each cycle through, but it's really up to you and how you feel. More on that in the program itself.
Finally, the last thing we do on any training day will be conditioning/muscular endurance based, and is intended to reduce the speed at which you fatigue, and improve your base level of performance. The aim of this is to leave you pretty smoked at the end of the workout, and to build your toughness.
In addition to the gym days, there will be a prescribed amount of 'homework', which is exactly what you're afraid I'm talking about - a total number of reps of a few bodyweight movements that I want you to achieve each week in addition to the time you spend at the gym. This will also help build up supporting musculature and increase the efficiency of the time you spend in the gym.
The other more general point to have in mind is that consistency and effort trump everything. Not every day will be a good day. Showing up over a prolonged period of time is what counts and leads to substantial gains. No individual day is important performance-wise, unless you're skipping it altogether.
Programs
I will give you a week by week template, to try to help you set small, manageable goals each week for improving aspects of diet and training. I will adjust from week to week based on the feedback you give me, although we will not change the exercises themselves until we've done them for 3 weeks at least (and we may not change them at all for 12 weeks if they are all working - measured by the improvement of the primary movement).
Diet:
It is important to reiterate that unless we sort this, everything else we do will be in vain.
Week 1.
The main goal is simple - I want you to eat 3x daily. Timings are up to you. Calorific make up is up to you. You can eat more, you can eat less, for this first week, I don't mind. You just need to start by setting the habit of eating 3x each day. We'll worry about calorie content and food choices as we progress. For now, just focus on 3 meals each day, whatever it takes.
You also have a sub goal - add one more fruit/vegetable to each day's diet. I expect you to hit this sub goal at least 5/7 days, and you should be disappointed if you don't make all seven. Consistency and commitment at this early stage will stand you in good stead when things get tougher later on.
Training.
Week 1
Workout A:
Bench (flat or incline, up to you, but pick one and it must be a free weight) - 1 x 5 @ 27.5kg, 1 x 5 @ 30kg, 1 x 5-10 @ 32.5, 1 x as many reps as possible @ 27.5kg - the top set is a best effort, stopping 1-2 reps short of failure and doing no more than 10 reps maximum, the back off set at your first set weight is a best effort rep PR. I suggest you warm up with 10 reps with the bar or some pressups, and then go straight into these weights.
Incline DB bench (doesn't matter what you did for your first movement) - 3 straight sets of a weight you can hit for 8-12 reps. This will build strength and mass to support progress in the main muscles of the primary lift.
dumbbell rows - 3 sets of 10 - 20 reps. If you hit 20 reps with a set, add weight to the next set. If not, keep the weight at that level for this exercise until you have a set (however many weeks it takes) that reaches 20 reps. This will build the antagonist muscles for the bench (your back), improve your benching platform, and give you thick, attractive muscles in the back
Rear delt raises - 3 straight sets, pausing at the top of the movement, as many reps per set as you can. Pick a weight you can do at least 8 reps with, and that is light enough that at any point during the movement you could pause and reverse direction. Use the reverse titty machine if you have one, up to you, just get it done. This will keep your shoulders healthy and make you look rounded in profile.
Conditioning: 20 burpees - take as many sets as you need, but make a note of how many and how long it takes you to complete this, and push yourself to be out of breath by the end, because you get to go home when you're done. This aspect will get more demanding over the weeks, but too much too soon will beat you up and I don't know what your level of fitness is.
Workout B
Squats (free weights, with a barbell, front or back squats, whatever you like, pick one and stick with it) - 1 x 5 @ 30kg, 1 x 5 @ 35kg, 1 x 5-10 @ 40kg, 1 x as many reps as possible @ 30kg. The starting weights are the same as your current work weights, as you should be able to improve this lift the quickest, and I suspect you can lift a good bit more once you have some confidence in it.
Stiff leg deadlifts (barbell or dumbell, up to you, whichever you feel happier with) - 1 x as many reps as possible, look up a video if you're unsure on form. Start out light, it's only assistance and we can add weight over the weeks as you feel more comfortable. Focus on form and get a pump in your back and hamstrings, stop short of failure by a few reps.
Chinups 3 x as many as possible, go to failure or thereabouts, whatever you're comfortable with, you'll be pushing to do more total reps week on week, so push hard, but keep the bigger picture in mind
Conditioning: 200 BW squats in as little time as possible. Note the time it takes you and the number of sets. We are going to build up to being able to do 500 in sub 10 minutes as a good guide to fitness.
Workout C
Military press (barbell) - 1 x 5 @ empty bar, 1 x 5 @ 22.5kg, 1 x 5 - 10 @ 25kg (push press it if you have to, just get used to moving weight in this plane of motion) 1 x as many as possible with the empty bar. This will build your shoulders and improve your general pressing strength.
Plate carries (bearhug as much weight as you can handle and walk with it) - 3 x as far as possible, try to note the rough distance so you can beat it next week. This will build the upper back and core to help stabilise your military press.
Chinups - 40 total reps for the workout. You can do sub-max sets inbetween sets of military press if you like, and you might find it makes your shoulders feel good. Doesn't matter about set numbers (keep a note though), just hit this many reps and move on.
Rear delt raises - 2-3 sets, 8-20 reps. Same principle as Workout A.
Conditioning: run 1.5km. Record the time it takes you.
Additional 'homework' - 100 total reps of pressups. 50 total reps of pike pressups. 100 neck raises (lie on the edge of the bed, with your head over it, and curl your neck (UNDER CONTROL) up and down), 200 situps of any kind you like.
You can do this however you like, on whatever days you like. Before bed, while the shower is heating up, while the kettle is boiling, while you're cooking

, etc. Don't worry about sets, just get them done, it's about improving your own expectations of yourself and increasing your work capacity gradually.
I have tried to be thorough, but I've been writing for an hour and a half now, so I may have missed something. If at this point you bail on the program, I will hunt you down!!!!!
Disclaimer* you should see a doctor and get a full checkup before undertaking any form of exercise. I am not a licensed medical practitioner.