Welcome to the forums, Moo!! Tough situation you and your fiance are living in at the moment, eh?? I have a couple of suggestions for you -
After doing a search on this forum for recipes with ingredients that sound good to you, you might check out Better Homes and Gardens website - bhg.com - there are wonderful an easy recipes in their files.
A book that I like for casseroles is "The Big Book of Casseroles" - you might look in your library for it or check on Amazon.com and see if they offer used copies for next to nothing, dollar wise.
My last suggestion, I know they will have in your library - look for any of Rachel Ray's cookbooks, 30 Minute Meals, etc. These are all easy and fast.
No, this is my last suggestion - Sandra Lee's books. They are all called Semi-Homemade, another good source for ease and quickness.
Good luck and let us know how you both fare.
Oh, lunches - like tuna? How about mixing tuna, hard cooked eggs, mayonnaise/miracle whip, pickles (chopped) for a filling. If he wraps his lettuce separately and adds to his sandwich at lunchtime, it won't be soggy.
There are all kinds of convenience foods in the market aisles now, pudding and/or fruit cups, little bags of chips, big bags of cookies, etc.