I happened to be working out the cheapest possible things you can eat and live a week on from tesco.
A week = 14000 calories.

52p 5250kc Tesco Value Plain flour
52p 5250kc Tesco Value Self Raising Flour
91p 2000kC Tesco Stir Fry Oil
75p 1800kC Tesco 500g cooking bacon
76p 600kC 2Kg Tesco Market Value Carrots.

Around 3.50.

If this was a month, you could add a couple of bags of sugar, add a 2Kg pack of onions, and get by on well under 15 quid, even with a rather more varied diet.

For the most basic above - there is fairly little you can do that isn't quite obvious.
Make a dough from flour + water + oil, then cook it with a bit more oil in a frying pan, after doing the bacon.
Carrots as snacks.
(speedevil, Mon 30 May 2011, 21:50, 2 replies)

noodles for about 11p a packet
cheap bread at roughly 20p per loaf. noodles and toast, standard student fare.
( Smash Monkey lowering the tone of the whole internet, Mon 30 May 2011, 21:58, closed)

Yummy.
How much for a bottle of tesco value vitamin supplement, I wonder.
( 4Q just lurking, Mon 30 May 2011, 23:12, closed)

57p
(insomniac-surfer oh go on then, just this once, Tue 31 May 2011, 0:22, closed)

a bit steep

( Another_tragic_case wished he hadn't eaten all the cake, Tue 31 May 2011, 9:50, closed)