Hi Paul. My wife and self went to Britany for two weeks and as it was our first outing abroad with the caravan we went with select sites of abergaveny (www.select-sites. not sure whether co.uk or com.). We stayed at Camp Du Lety at Benodet. They arranged every thing for us, all we did was arrange passports and euros.
We sailed from Plymoth to Roskoff thinking we would do most driving in this country. The road from Roskoff to Quimper was excellent dual carraigeway - the only down side was the lack of petrol stations on this road.
Benodet was beautiful as was all the area. The site was spotless and right on the beach (50yd. walk out of the van to the beach). We were approx. 15 minutes walk via the coast path into Benodet. We covered approx. 1000 miles without any problems, the streets and beaches were spotless and the sceanery was fantastic. Don't worry about driving on the wrong side of the road, I had no problems what so ever, your main concern is to pull out when overtaking. Roundabouts are all clearly marked which way to go.
I would recommend that you contact select sites and obtain their brochure and pricing, we will certainly be using their services again.
Good luck and enjoy your new found pleasure and happy caravaning in France.