When you see cheese sauce on special offer (reduced to like 25p), grab it and freeze it. Then pasta with a handful of frozen broccoli, peas, spinach, green beans, in the cheese sauce. Or you can make the cheese sauce but that is more expensive.
Sausages on special, or just cheap ones. A tin of haricot blanc, 6 sausages, 2 sliced onions, 1 pint stock, a bay leaf: fry the sausages and the onions, tip in the beans and cover with stock and bay leaf. Simmer until suppertime.
Pinto beans, in the slow cooker with a tsp of lard, chilli powder, half an onion, plenty of water. On low for 8 hours min, then you can either freeze at this point and refry from frozen, or refry now and freeze the finished product. Good for wraps, sandwiches, omelettes - bulking of all kinds.
Leftover mash (you can freeze this), a tin of salmon (about 75p at Lidl), a sliced onion, any seasoning you fancy, ananegg (about 25p). Squidge the fish and mash together with the egg. If you have breadcrumbs (in the freezer, aye), you can dab the patties in breadcrumbs, but it's not necessary. Bake in the oven or fry according to taste and serve with a giant pile of green veg (your frozen peas, beans, spinach etc again).
Mash can be any root veg: add in sweet potato, carrot, parsnip, celeriac, whatever is cheap. Sweet potato is cheap in Lidl and asian grocers, celeriac is cheap in farm shops.
hth, sorry for going on