Try the energy bars from this site, they turn out so well! And all the ingredients together should definitely cost less than buying the same amount of Larabars or something similar. Other easy grab meals/go to snacks can be precooked bacon (as in cook a bunch on Sunday and keep it in the fridge to reheat later), hard-boiled eggs, cheese sticks if you eat dairy, frozen berries, and almond butter. Those are the easy things in my kitchen right now anyway.
Whenever I have a stressful time coming up I just keep reminding myself to take it one day at a time. Get the things done today that you need to/can get done, and don't worry about tomorrow just yet. I also like making lists (for everything really), just to keep myself on track. Exercising should help too, but don't beat yourself if you don't fit it in every day! Take deep breaths, stay in the present, and you'll be fine