Yes, need ticket for Zones 1 & 2 - about £4ish.
Cheers Diello ;)
Just a note RE the Earls Court switch, leave PLENTY of time as its a one in six shot that the tube goes to Olympia and the station is a BOMBSITE as its being knoced to bits and actually becomes prity much closed in about a week or so's time, so the platforms are tight, covered in scaffy etc.
My advice (I've been to BETT today as the guys on the stand will confirm and if you watched the webcam at the right time I was on it!) If when you get into Earls Court station, do rush to the stairs up to the platform especially if you can hear or spy a tube in the station RUN up the stairs and read the signs as that may be the last Olympia train you see for 15 minutes!