If I was you, I would spend money upfront on a sack of LIDL potatoes for £3.50, 2x 1.5kg bags of flour for £1.20 , a packet of yeast for a quid, a packet of chickpeas (can't remember), a packet of red lentils for 75p, a packet of frozen peas for £1,a packet of carrots for 60p, 2 packs of pasta for £1,lots of tinned tomatoes, a bag of onions for 60p, a kilo of porridge oats for 75p, 12 eggs for £1.80,and a packet of Basmati rice for £1.00. (These are all LIDL prices, and not 100% accurate. All packets are whacking great generous ones). I make that £20- ish, although my arithmetic isn't what it used to be.
You've then got the makings of endless dhal, potato and pea curry, carrot and red lentil soup, bread, scones and pizza (if you add some mozzarella, which is actually the cheapest cheese you can get!), chick pea pasta (fry cooked chick peas up with onions & garlic, add some rosemary you've nicked from someone's hedge, add half a tin of toms,squish about half the chickpeas up and leave the other half intact, and there you are), porridge (with milk), jacket potatoes with nearly coleslaw or spicy chickpeas, egg fried rice w/ peas, etc.etc.etc.
Can you get powdered milk- at least for you?
Good luck! 