Sorry for the late answer, I just noticed I had a message in my message box...

The best rugby club in the region is without a doubt Plouzané AC Rugby, but they are Plouzané is nearly 50kms away. They play in the lowest national amateur competition, the Federal 3.
In the Federal competitions, you can find Brest UC who play in Honneur (Groupe A)
You have a club in Landivisiau, playing in the competition just below, Promotion d'Honneur (Groupe B) :
One step below, Groupe C, you have a club in Morlaix ( ) and in Landerneau too (

Wish you a good landing in Britany, thats really a nice region.

Friendly, Jean-Noël