A month ago we spent three weeks around this area, loads of places to go, the weather was very poor, only three days of sunshine in three weeks (very disappointing).
The islands (Les Glťnan, HoŽdic & Houat) all have anchorages with varying depths, but can be exposed and if you are planning a night stop the weather must be settled (these islands donít have much high land and so donít offer much shelter)
Belle-Ile on the other hand has high land.
If the weather is unsettled head into the Golfe de Morbihan there are loads of moorings/anchorages, l'Ile aux Moines, Auray (Bono), l'Ile Long.
There are loads of other places, like l'Ile de Noirmoutier, Pornic, Ile d'Yeu to the south, and Etel(interesting entrance) l'Ile de Groix, Aven and Belon Rivers (famous for their oysters if you are into that!!), Concarneau, Port De La Foret, Ile Tudy, Beg Meil, Benodet, take your choice, it just depends on how far you want to go and what the weather is like? We have been sailing this area for the last 40 Years (only missing a few summers!!) and it has changed quite a bit, mainly more boats!!!!
I think you will need to decide where to go when you are there and get a forecast!! We changed our plans a couple of times!!!!