Hint 1:
If you see 'value' stuff in the supermarkets, don't knock it unless you've tried it!
For example, I've tried some 'value' lasagnes and decided 'never again' but I've also tried 'value' mince (just as good as the expensive stuff) and 'value' spag-bol (a cheap & tasty snack) as well as many other 'value' products that are perfectly acceptable.
Hint 2:
Remember that (for some strange reason) frozen foods are often only around half the price of fresh ones. Again I'd recognise that a few might turn out to be rubbish but my maxim of 'don't knock it until you've tried it' applies to most of them, which are fine.
Hint 3:
Buy lots of cheap ingredients and work out what you're going to do with them later. For example, I buy 'value' mince (around £1.50 for 500g) and freeze it in 100g portions. I also buy lots of 'value' rice and 'value' pasta, together with 'value' chopped tomatoes. Then, with just a few extra for perhaps 60p per meal.a ingredients from my store cupboard, I can make curries, pasta dishes and lots more.
Hint 4:
Keep an eye open for cheap stuff which can go into casseroles (particularly if it's something which can be frozen). For example, Asda were recently selling some really good Lincolnshire sausages at just 75p for a pack of 8. I freeze them in 4s and I've then got a basic component of sausage casseroles for some time ahead.
Hint 5:
Don't buy expensive 'cook-in' sauces! Pound shops sell cup soups at 2 packs (of 4 or 6 soups per pack) for £1. Cup soup (made a little thicker than usual) makes a great base for a casserole. Asda also sell a really good 'value' casserole sauce, in a jar, which goes really well with those cheap sausages I mentioned.