"With the U.K. having left the European Union on January 1st, 2021, the procedure for U.K. boats entering the Schengen area has drastically changed.
Over the last few months we have made representations to the regional maritime authorities in Brittany for clarification on the subject, and following the latest information that we have received from them, we have prepared a guide for those wishing to visit marinas in Brittany."
Click here for a copy of the Guide
Note, the CA are reporting (14/8):
" We have now had notice from Customs Officials in Brittany that all visiting vessels arriving from outside of the Schengen area or European Union must first visit a Port of Entry. This changes previous advice that they were moving to a system allowing notification by emailed form followed by a visit to a port of entry.} "