O2's website has now been updated. You can now sign up for new lines and move from other suppliers.
I entered my details for a TalkTalk line and for the first time it has said I could.
Apparently 'they need to do something extra to my line' and therefore want to charge me £45 for the privilege.
Hmmm, is it worth the £45 to be shot of TalkTalk, I'll have to think this one through!!