Halifax Instant Saver
http://www.halifax.co.uk/savings/instantsaver.asp
probably looks the best bet
Halifax Liquid Gold
http://www.halifax.co.uk/savings/liquidgold.asp
though interest ain't as good as it used to be...... had one of these since about 1988
Both these do special rates of interest for savers under 21yrs old
Not sure if you're old enough to open a Halifax variable rate websaver (you can always try... if not, maybe when you're older)
http://www.halifax.co.uk/savings/variablewebsaver.asp
For further advice on Savings accounts, check out:
http://www.fool.co.uk/savings/information/easy-access-savings-accounts.aspx
http://www.fool.co.uk/savings/information/how-to-save-more.aspx