In reply to Gemma_Penny:
I rather fancy you've set yourself an impossible task..but my recommendation would be the South of France. Le Sud is, of course, BIG, so a bit of foreknowledge wodul help you out.
the most obvious place on the coast is Les Calanques near Marseiles, but the Gorge de Blavet (near St Rapahel) offers north facing routes, and I really like the gorge du Loup and St Jeannet a bit further inland near Nice.
There's much more to go out, but I mention these since they are all featured in Rockfax's guide: 'France: Cote d'Azur'.
Stil, there's no escaping the act that heat/humidity will be a huge issue. In general, people like me, who spend a ot of time in France, tend to stick to the higher mountain crags in August, largely safe from the ravages of tourism and le soleil.
hope this helps.
John C
John C