The Q&A session from London Expo is now online, and can be found here:

http://geeksyndicate.wordpress.com/2008/10/30/merlin-panel-and-press-interview-at-london-mcm-expo-2008/

At that link is also a recording of the press Q&A session, which took place backstage after the panel.
There's some really great talk between them all, both about the show, the fans and the slash. Well worth listening to, if you can :)