France has some of the least restricted airspace for VFR flight in Europe.
The airways are class E up to FL115 so my recomendation based on experience is to stay VMC and get as high as possible......keeps you out of the low level military areas.
If I was doing that route again, I would do Le Touquet, Lyon Bron and then Bastia. How direct a route towards NIZ area is up to the weather and MSA.
DFC