How many are you cooking for?
Spanish omelette, cheaper and more filling than your average omelette plus you can eat it hot or cold for lunches, using up potatoes onions anything you want. Jars of peppers can come in handy as they stay fresh and you can put just a few in things like this. You can get huge jars in tesco etc cheap
Veg stew - I use up anything I've got in, always potatoes and onions carrots stick cubes, but either your traditional veg like swede etc or I do aubergines chick peas etc sometimes add chilli flakes, I almost always add either red lentils or barley or both.
I've recently discovered the weigh your own, eco friendly shops.
I got oats, muesli, lentils, cinnamon sticks at a fraction of the usual cost so its worth looking up ones in your area.
I also love to yellow label shop in supermarkets, if you go in the evening there are usually bargains and I often fill my freezer. We have several vegans and a few meat eaters so it's good to save money as much as poss and give everyone variety.
Burgers are good and filling, home made sweet potato wedges,
Massive bowl of home made coffee slaw costs pence lasts days and is so much tastier.
Big slow cooker of risotto, mushroom is good, we just use Normal mushrooms whatever is cheap, rice and onion and stock cube.
Pasta bake , with cheap garlic bread or make your own.
I like to make a tub with fresh garlic in a tub of flora or whatever, then bake baguettes and use that but it's also so good on anything and just for dipping!!
Big home made quiche will do days of lunches
Wraps packed with salad, ham coleslaw
Cous Cous , falafel , Greek salad
I would definitely contact a food bank in your area xx