Quote ="PONNER"We're camping on Friday night about 13miles from Wembley then taking the tube from Cockfoster on Saturday morning.'"
Get an Oyster card! You can pick one up for a fiver( Which is actually credit!)at your start up station but your journey from Cockfosters to Wembley will only cost £1.10 whereas the normal price is £3.20 single! A travel card will help if you can't be bothered with the oyster card though even then they're £5.10. At least a oyster card is usable and top up-able for anyone you know for future uses of the London Transport! I used my mums for Quins and it saved me quite a lot!
[url=http://www.tfl.gov.uk/tickets/oysteronline/2732.aspxDetails here[/url