If I was a musician with Richie's problems I know that actually playing live would be part of my recovery - if he's not in the UK I would be completely pissed off and I'm not even going to the show!

I'd be pissed off for Laura and Thierry who are going and spent around £100.

There is no way Richie will have recovered by the time they come to the UK. I just hope he's prepared to play a show whilst he is still a little screwed up. If he or those close to him aren't prepared to let him come to the UK to play then I think it will be a huge disappointment and in the circumstances you should postpone the show (not that they will because they don't want to lose their "first band to play O2" history statement).