Just thought I'd mention... Why not consider taking a bus?
Yes, it can be a bit wearing sitting on a bus for 18 hours, but on the other hand:
It's cheap (variable, but approx £150 return Cardiff to Chamonix all in) No transfer fees, parking charges,expensive waits in airports, luggage charges ..
It's more environmentally friendly than flying (I think..)
There's no security to speak of, so you can take gas cylinders, ice axes, crampons... And as big a rucsac as you could wish.
People are friendly and you get to see a lot of countryside.
Just been to Cham and back and I was the only climber in either direction.