We are off there on the 22nd of this month, Taking the ferry from Portsmouth to St Malo, then a short run down to Cap Coz near Concarneau. We will stay there for a few days and then run down to St Nazaire, cross the Loire there and then run down the coast to Saint-Jean-De-Monts.
Brittany is lovely this time of year, especially Concarneau as it is a walled city in the sea, well worth a visit and Quimper has a beautiful Cathedral. The coastline from Concarneau to Bénodet & Plomeur has some lovely beaches including Cap Coz and you can watch the fishermen come in with their catches at Loctudy. Fouesnant has a wonderful traditional market, well worth a visit.
St Malo to Concarneau is 140 miles, approx 2 and a half hour run,
We usually catch the overnight ferry at 11 pmish from Portsmouth using it as an Hotel, arriving fresh in the morning about 7.30am (French time) straight on to the D768, then the D790, then follow the signs for Concarneau.
Are you planning to start at Calais and finish at Caen or the other way round?
You will love it Taffzee, Billz is right about the bridge at St Nazaire, it is massive, but you are down into the Vendeé, across the Loire at that point and no longer in Brittany.
PM us is we can help anymore.
Mike & Sandy