The best way would be to go somewhere where you have friends, so you can stay at their place, I'm sure some of HLPers would be happy to oblige. Tenting is also an option, but this a) limits your traveling options, for instance you won't want to tent in Poland, anywhere, and finding tenting places in other countries is tiresome and hard, plus a lot of planning is necessary. Of course, if you rent a car, that'll ease up things a lot, but means an extra £30 per day.
If you're traveling beyond may 1st to somewhere in Eastern Europe, forget about visas, won't need 'em, since we're in the EU by then. Also, if you need recommendations about possible destinations, then Hungary and Chezchoslovakia are both cheap and horribly beautiful (Budapest and Prague + the wonderful nature in Chezchoslovakia). They are the first places I think of that give a wonderful cultural and fun experience, yet are on the cheap side, and slightly further away from the usual Englishman destinations. The living costs in Chechoslovakia are lower than a funnny comparison that escapes me at the moment. Plus they sell software for £2.
Aside from making sure you have health insurance n' ****, and adding 30% to everything you expect to spend, I have nothing more to add.
Ask me, if you want to know.