First UK Travel!

Hey guys!

I'm looking at traveling to the UK next year for my birthday - March 2011. This gives me time to finish school, save up, etc.

Things are coming together, but i'm trying to figure out how much money i'd have to save up.. I want to stay at some hostels, some friends houses, etc.

Any idea what a good amount to save up would be, if I was going for a month? Obviously it depends on how much I spend, etc etc. But I just need a rough idea.. i'm not sure where to start. (My answer - is as much as possible.. but.. maybe someone can give me another idea to branch from?)

Thanks!

-Heather