Tricky choice - several UK banks have offshore operations offering euro accounts (Citibank, Nationwide, HSBC, Barclays at least, probably more). Big problem is guessing where exchange rates are going as the best interest rates on a euro account are likely to be over 3% lower than sterling accounts. Advantage of having (some of) the cash in sterling is that you can bung some of it into tax-free/efficient accounts.
Haven't looked at how to quote previous threads yet (..awaits deluge), but if you search this site for 'currencies.co.uk' there is a discussion on converting pounds to euros which I suppose would work the other way round.
For interest, Interbank Pound to Euro exchange rate for today over last 4 years:
2002 - 1.586
2003 - 1.402
2004 - 1.484
2005 - 1.451
(numbers from
http://www.oanda.com/convert/fxhistory )
As you can see, you could have broken even, lost money, or gained money depending on when you moved between sterling and euros... Current forecasts are for sterling to decline against the euro, but zillions of different forecasts about how much and when (ie most of them will be wrong).
Alternative option: take a gap year and blow it on Wine (France), Men (Spain/Italy), and Song (Greece)...