[Closed] Exeter To La Rochelle – Any advice

I am embarking on a solo road bike tour from my house in Exeter to my girlfriend’s family in La Rochelle in a couple of weeks. This will be via the Plymouth – Roscoff ferry, then cycling down through Brittany into La Rochelle. The bit from Exeter to Plymouth is sorted, I have a route in mind and despite being a bit hilly I’m sure I will be ok…
Any recommendations for a route down through France? Google maps reckon it will be 280 miles by avoiding highways, I will be aiming to do 100 miles or so a day, on a road bike with a tent. I think all my gear is sorted and all I need to do is plan a route. I would like to stay in campsites to allow me to have a shower and settle properly, and I was thinking maybe following Roscoff to Carnac, then Carnac to Lorient, then down to La Rochelle. Has anybody had any experience of doing a similar route in the area? If so, do you have any recommendations regarding campsites or roads to take? I’m travelling quite light; the bike is a Cannondale CAAD10, tent in a carradice, sleeping bag on the bars. I’ll be putting some 32 spoke wheels on with Gatorskins, but obviously I will need to focus on decently surfaced roads, any suggestions would be gratefully received.