Cruising along the Brittany coast between Tréguier and the Raz de Sein will exercise your navigation and pilotage skills. There are plenty of anchorages and towns to visit, so day sailing is feasible, with strong tidal streams. Catching the tide may mean a very early start. Going west, you'll be arriving at low water; passages east give you more destinations!
This is lightly populated holiday country out of season, but very busy in July and August. There are delightful beaches, and several isolated offshore islands to explore. Inside passages offer pilotage challenges. Big Atlantic swells are an occasional (sometimes dramatic) hazard, as are patches of over-falls. Two major tidal gates guard the entrance to Biscay. The first is the Chenal du Four, inside Île de Ouessant; the second is the Raz de Sein, notoriously rough with even moderate winds against the tides.