Well, I use a lot of own brand/smartprice ingredients which I know some people wouldn't but you can always substitute some or all of them for premium versions and these would still be cheapy meals:
Tuna veggie pasta
smartprice pasta 19p
asda chunky veg pasta sauce 81p
tinned tomatoes 21p
tuna in brine 37p
Green Giant Kidney beans 13p (or sweetcorn etc)
(pasta in one pan, everything else in another, cook, drain pasta, mix)
= £1.71
Cowboy Casserole
2 x baked beans 40p
2 chopped tomatoes 42p
smartprice sausages 16p
2 x oxo cube (works out at) 16p
large onion approx 30p
2 x tinned potatoes 44p
mixed herbs, mug of red lentils, tomato puree, garlic, mixed spice, mug of water
(fry sausages with onion and garlic, cut potatoes in half, add everything to big casserole dish, cook until lentils are soft and don't skimp on spices etc) Nice with green veg and mashed potato or crusty bread.
= £1.88
Cheese n potato bake
block of cheese approx £2
4 or 5 spuds approx £1
large onion or two medium approx 30p
few rashers of bacon (optional)
salt, pepper, parsley, milk
(fry onions til translucent and bacon til just cooked, grate cheese, peel and slice spuds, chop bacon. Layer up cooked onions, raw potato slices, cooked bacon and grated cheese in big ovenproof dish, pour over milk seasoned with black pepper, a little salt, mixed herbs etc, finish handful of cheese on top and breadrumbs or crushed crisps, if liked. Bake until potatoes are soft and all is brown and smelling lovely)
= approx £4 but depends how you make it. Best served with lightly cooked green cabbage or broccoli.
Peasants Soup
Onion
garlic
Two carrots
Two spuds
tin chopped tomatoes
tin butterbeans, drained
red lentils
Any other veg, cabbage, leek, mushroom etc
water, bay leaf, mixed herbs, salt, pepper, two oxo cubes, tbsp tomato puree
(Fry onion and garlic til translucent, rinse lentils, chop veg, add all to big pan, bring to boil then simmer for ages with lid on stirring occasionally)
= approx £2/£3 depending on veg added.
If you need it within the hour use tinned lentils and just wait for veg to soften. Serve with crusty brad, or herby dumplings. (1 part suet/veggie suet to 2 parts s/r flour, pinch salt, mixed herbs, cold water, mix and roll into balls, dump in pan for last 30 mins of cooking)