i dont personally (at the moment) have to budget myself, but I will soon when I go to uni.
All I can say is £60 a month doesnt seem that much, so your gonna have to be really strict on what you buy.
I think Tescos give you discount if you buy online (if u have a clubcard) or something like that, so u could save money that way.
its best to concentrate on buying basic items such as bread, eggs, etc and cooking everything from scratch to save money.
Sorry i dont really have any more info, but i'll check back and see what ervy1 else says cos I am crapping myself about having to start buying my own food ans budgeting soon!!!