Home Bargains is amazing for cheap treats such as 25p name brand chocolate bars, and store cupboard foods such as tinned tomatoes, noodles, tomato puree, even cheap quinoa. Also for cheap generic medications (paracetamol, ibuprofen, hayfever tablets, cystitis remedy sachets (less than £1 in home bargains, compared to over £4 in boots, same packet), tins of vaseline, tampons. Just dont be fooled by their £1 garden tools, very bendy trowels 
Try Aldi own versions (normally as good or better than big brands) and in big supermarkets try buying the value ranges in the supermarket. We challenged ourselves (ie made a game of it to avoid feeling depressed at being really stretch for money) and were pleasantly surprised by how good somethings are. I seriously regret never trying this when I was a student years ago, I kick myself thinking of how much money I could have saved.
We try everything once, and if the cheapest version isnt nice we don't bother with it again (not a fan of very cheap tinned sweetcorn, and will never ever go near the bargain basement sausages again). However we have discovered so many good products that are no different to ones costing £s more.
Stuff that we regularly buy (usually in Asda) include 20p tins of potatoes (mash, roast, use in corn beef hash, spanish omelette and never get wastes from being left sat in a bag to grow tendrils like other potatoes). Tescos value cheddar and Asda cheddar are both (imho) better than Cathedral City (I had cheese on toast every day during my pregnancy, I became a bit of an expert, tescos was cheaper, asda better melting). Asda value fish fingers, and golden rice are as nice a big brand ones. Our family gets through gallons of sparkling water a week, guess what...asdas 17p for 2 L.
Aldi Gin is excellent!!