1kg of frozen mince - £2.50
2kg of onions - £1.17
Tin of chopped tomatoes - 33p.
500g of spaghetti - 35p
Mixed herbs - 19p
Fry onions, add the mince, brown it off, add some of the herbs, then throw in the tomatos and some water and the rest of the herbs. Let it cook for a bit and then cook the spaghetti.
If you have any stock cubes, add that in as well.
Can easily add some chilli, garlic, pepper to change it up as well if you want. Kidney beans are 18p a tin.
The mince will do 3 meals or so, onions will last ages. It's not going to taste amazing, but it'll do you and you can change it to have a slightly different meal each night. Baked spuds are cheap, and will change this meal. As will serving it with rice with a bit more spice. Cook it down further and serve it in tortillas.
As said, porridge is cheap. I find milk cheaper in my local corner shops than the supermarket. You could do a 1:1 milk:water to increase the milk life if you wanted. I'd cut puddings out totally, or make a simple sponge cake yourself (weigh 2 eggs and then weigh that much sugar, self raising flour and butter. Mix it all up, oven it at 180 for 20 minutes. Sponge cake - done) if you really need a pudding.
Pizzas are stupidly cheap to do yourself, make a simple dough (flour, and water essentially). Let it have two rises for the best dough. Buy some pasatta for the sauce, reduce it down if you want. Throw some of your mixed herbs in to jazz it up, bit of cheese (will be your biggest outlay) and then whatever you have lying around to go on top. Remember, you can add frozen veg to a non frozen pizza and it should be alright. Likewise, start baking bread. You can probably pick up a huge bag of bread flour for the same price as a loaf nowadays. It'll take about 30 minutes of actual 'work' to make it.
The best way to save money is to look at your lifestyle as well though, not just food. Energy useage is key, as well as stopping luxuries (within reason - even when on a total budget, I'd still budget for a beer or two! - cheap beer, but beer all the same) and try to think of doing things for free. Walking vs. motor transport for example.