This is a common problem, the airways routes near Deauville all point the wrong way.
My top tip, since you are heading to the West of London would be to file
CAN G4 JSY DCT ORTAC N866 SAM R41 NORRY DCT
It looks longwinded, but it passes the Eurocontrol test, and in reality, the French controllers will normally route you direct to ORTAC for the crossing along N866
2D