Lentils are your friend! A large bag of lentils costing. £1.20 (bought red lentils yesterday) will make lots of meals, buy onions, mixed curry powder chilli flakes (or fresh red chillis if in budget) and ideally fresh coriander and a pack of creamed coconut (pataks contain 4 sachets) plus 1kg brown basmati rice and that will make 16 portions of dal. If you can afford it/have leftover add peppers, green beans, courgette, aubergine or anything really to change it but the above is the base. I worked out my coconut dal with aubergine at 59p a generous portion (lidl prices, rice bulk bought from Asda world foods). Ps brown basmati is healthier than white so a good choice if on limited budget.
Mixed bean chilli is another cheap option take a finely chopped onion, finely chopped carrot and sauté, add a can of mixed beans, a can of chopped tomatoes, oregano, chilli and cumin (or lidl have chilli seasoning at 29p a pack, you only need half a pack for this) and cook, serve with rice and if you can a sprinkling of cheese.
Chopped bacon / lardon risotto is another go to of mine. It's a two pack for £1.50 I serve 3 people with one pack.
1 pack lardons (half a twin pack) one onion, 1 lemon, 1 cup risotto rice (lidl is cheapest) 1 vegetable stock cube (or chicken) dried oregano or mixed Italian seasoning plus back pepper, whatever cheese you can afford.
Fry lardons with onion, add rice and zest of lemon, add 3 cups boiling water plus stock cube, add seasoning, add lemon juice. Cook until rice is done, add extra water if needed. Add cheese - dried up cheddar gone hard can be used, obviously Parmesan but I've used a bit of Stilton found in the fridge, "Italian hard cheese" or even a "cheese fondue" bought and gone out of date! Add any fresh herbs you have but not essential, can also add green beans, spinach, asparagus or similar if left over from other meals. This serves3 portions