Welcome to the real world
You should have gone to uni somewhere cheap. Like Middlesbrough or Newcastle. That way you could have done what I did at uni, drink lots of beer, eat take aways and fail to sleep with increasingly unattractive women!
Sorry to say but you either need to budget better, and cut your cloth accordingly as they say, or get more income in and that means a job. I thought I was really careful at uni but when I lost my job I found out how tough things are when you get very little income and your savings have run out. I would suggest the following:
1) Shop at Farm Foods, Netto or Aldi (if you can/have any near you)
2) Buy things like meat and fish from the going out of date section of your supermarket. Break down the product into daily portions and freeze on the day of purchase
3) Keep your bread in the fridge. This will extend its life for toast and things for up to 10 days (worst comes to the worst just cut the mould off)
4) Dont eat prepack meals. Cook wholesome stodgy filling meals. Batch them up and freeze them
5) Dont go home as often/ever ( hard but necessary)
6) Turn EVERYTHING off. Leave nothing on standby. Even turn the microwave off to save money on running the clock. Become a Nazi on energy efficiency
7) Dont use a tumble drier - they cost a fortune
8) Cut down everything extra you dont need. Sky/fancy phones/Cable/Gyms/broadband package, whatever it is dump it or change it downwards (if the contract allows)
9) Close all the doors in your house. It will keep your rooms warmer longer. Sounds silly but I bet your rented house doesnt have great insulation.
10) DONT use those little Tescos or Sainsburys. They rip you off in the name of "convenience"
11) Walk or cycle everywhere you can
12) "Borrow" as much stuff as you can from uni. Charge your phone, I pod, e book etc there and not at home.
13) Sell anything you dont need on Ebay
14) Darn your socks! (My feet rot socks and shoes!)
15) Dont pay for anything you dont need dont get food delivered, walk to the shop and get it yourself!
16) Use markets for fruit and veg. Even meat and cleaning products you can save a fair bit doing that.
17) Take your own lunch to uni. Cut out the pre packed butties and the takeaways
18) If you have a credit card get rid of it if you can. It is too much of a temptation to use it for things you shouldnt
19) If you can shop around for your energy supplier.
20) See if you can get a water meter fitted.
21) List out what you need for your food shopping. Stick to it and dont buy that nice looking pie or cake! Silly but it really helps focus on your spending
22) If you have insurance think if you really need it or if you do whether you can move to a cheaper option. Ask those meerkat people!
23) If you have a car get rid of it if you can. I have no car now and seem better off not having to fork out for petrol!
24) Learn to say no to things and stick to your decision.
25) Look on the net for money off vouchers for your day out.
26) If you smoke try and give up!
27) Dont do the lottery or gamble (if you do) you wont win often enough to make it worthwhile (Although I used to live on my nudgie winnings!)
I guess you have done all of this but it does help sometimes to see it written down.