In reply to wig:
The beldoire campground is the closest to the climbing,and in fact the climbing between Pas de Souci and Shadocks sector(in topo now 9 yrs old) is some of the best in the gorge,gleaning info on these areas is diffucult though!They are easy walking distance from aforementioned campground.Hitching getting lifts I would imagine is easy as you are going at the hight of season.
We are at the tarn(well in millau being rained on) right now its an awesome place possibly 700? rts here now....
We flew to montpelier...you can catch train to Bezier and change to Millau or catch coach dt to millau from Montpelier