I usually buy a bunch of 4pack white albacore cans (the small pop top cans) and keep 1 or 2 in my gym bag etc. just drain and eat out of can. Yes all natural peanut butter is excellent. Read how I make my oatmeal in that thread it is very filling and lasts a good while plus provides protein, potassium, and starches (good carbs). Actually tastes good too, a little heavy wait an hour before intense workout if you can.
It's hard to change your lifestyle but once you fall into routines and see how your body reacts to this it will become easier. One of my coaches sells a program through the pro shop that utalizes 5 or 6 heat or mix meals that are balanced to exactly what you need plus 1 lean and green that you make (oh ya brocolli and spinach are great for you). After a month you take off 1 ready made and add a home cooked and so on. This program was developed and tested by NASA and has proven to be effective. What it does is teach you ow to adapt your lifestyle, the food is just a tool to help you. I thought it would be expensive but the breakdown for the first month is approx $8/day which is 6meals cheaper than one trip to a fast food place... made me think. I may switch to it if I am cutting to a fight weight but for now I am good on my way to 200lbs and wanna be at 185lb fight weight.
Also I don't know your fitness assessment so these are all just general good practices.
Check out menshalth.com though they rank your best proteins etc by value and all kinds of stuff its great.