I'm now a poor graduate rather than a poor student, but here are a few tips I've picked up.
*
The first may sound a little odd, but most of the very very cheap recipes I use are from when my mum did Slimming World. They also have the benefit of having loads of veg. One of the nice ones is a layered bake of thinly sliced potatoes, tinned tomatoes and thinly sliced onions, for example.*There are loads of Facebook groups etc. where people are sharing budget friendly recipes in family-size portions which are handy for freezing, and a lot of these come in at under 50p a portion. Lots of the 'Feed Your Family for £X' pages have good recipes you can make in bulk.*Pancakes are one of the cheapest things you can make, and are good sweet or savoury once you get the hang of making them.
Bacon and cheese are one of the cheapest ways to add a lot of flavour to a potato or veg-heavy meal. Eating cheaply doesn't mean your food needs to be bland. Finely diced rasher of bacon is good with pretty much anything and a sprinkle of grated cheese goes a long way. Frozen chicken is often a lot cheaper than fresh, and tastes fine. Sausages are one of the cheapest fresh meats you can buy, and are very versatile, for example, they can be removed from the skin to make burgers, meatballs, broken up for a chilli con carne or a pasta bake. Don't buy a lot of seasonings - salt, pepper, chilli flakes (if you like spicy food) and Italian seasoning are the few that I would recommend, but consider what you actually enjoy eating, too, before you make any decisions. If you love Chinese food, for example, splashing out on some soy sauce, sesame oil and five spice is probably a good investment.*
There really is no need to shop outside the 'basics' range in the supermarket for most things. Pasta, tinned tomatoes, oats, rice, bread, frozen veg, all come in at pennies. Frozen and tinned veg is also absolutely fine to use, and much of it is nutritionally very similar to the fresh versions. Don't be scared to make adaptations either, for example, if you were making a creamy pasta sauce there is no need to splash out on creme fraiche or cream that won't get used, just use milk instead and cook it down slightly. If you can, shop at a Farmfoods or Heron Foods, as you can get frozen foods for next to nothing. Most supermarkets sell a soup or root veg pack for around £1 which will have carrot, parsnip, turnip and onion at least, which makes quite a lot of soup, and all you need is salt and pepper (and a stock cube if you have one).*
My last tip is to try and get excited about cooking your own food from scratch. Not only are you eating cheaply, but you're avoiding processed foods, additives and preservatives, something people pay a lot of money for nowadays. Spend time looking at easy recipes online (BBC Good Food is great for this) and watching cooking shows to get inspiration. Adapt things to make them easier or to suit your taste and save the ones you enjoy (either in a notebook or a word document works well).