We stayed near lorient and in Trinite sur mer near Carnac - lorient was a bit too built up but had a great Celtic music festival. Trinite was a lovely spot - we stayed at campsite beg meil which was a very good campsite - small and relatively quiet - kids had a great time although pool complex was not very big - trinite although close to Carnac was quieter (the roads around carnac can be a carparks at times). trinite also has lovely marina and you can walk to town from site (about 10-15mins) - beach is just accross the road from the site.
Regarding travel from Scotland - unless you are going for more than 3 weeks personally i would fly - probably cheapest to paris and hire a car - tends to be same or lower cost than driving and ferries and saves about 2 days travel.

We have made this trip several times from Scotland.

We used to drive South on day 1 and then get the boat the next morning. After a couple of these trips we thought it would be better to just drive straight on to the overnight boat. However "overnight" is a bit of a misnomer as you have to get up around 5.30, and after a 500 odd mile drive you really need a good night's sleep! We didn't do it again.

Have you considered the Rosyth to Zeebruge option? I think it's qiute expensive, but it would cut out some of the driving.

Did it the last couple of years, staying in Noyalo, which is around 10km from Vannes in the morbihan gulf. With regards to the driving, we just left early in the morning and drove down to Portsmouth in plenty of time (take the M6 Toll Road bypass, its worth the £3 ) I didnt mind the overnight ferry (good entertainment on board!) although it can be quite a drag on the way back when its a day ferry! Then we only had a short drive (1 hr and 30mins) to Noyalo, and the roads in that area were pretty good, although not much dual carriageway.

Dont know too much about local campsites (looked like a nice one in Penvins though) as we stayed in a villa, but i do have a lot of pics, etc, of the morbihan gulf area on my website, so have a look if you want, and get in touch if you need any more help, it's all still fresh in my mind at the moment!

I would recommend L'Atlantique in Beg meil (Fouesnant), Southern Brittany.
You go through 400 meters of beautiful woodland to a magnificent beach and is one of the best equipped campsites I've stayed at.Great waterpark with a cute toddlerpool, well serviced with shops nearby and helpful reception staff.Excellent for kids of all ages, even little ones.
It's not a bad drive from the ferry and is about two hours or so from Roscoff.Carnac is a bit further down, where we stayed at the supposedly good campsite Le Grand Metairie.It was great for teens but we felt that the campsite was so large, the younger ones found it a bit of a long walk to get to the pool area.
Driving in France is fine really.The roads are so good it's hard to go wrong.
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