Hi Ian,
We have just returned this week from a trip to France via the Portsmouth / St malo route.
We thought it was an excellent route. Coming from North Wales it made sense as we could drive down all day to Portsmouth and then get on the night crossing.
We had a cabin for the four of us and managed to get a good 7 hours sleep and breakfast before we arrived in St Malo at about 8:15 local time in France.
This then gave us only a 3 hour trek down to St Jean De Monts. On our site for lunch.
Coming back we stopped overnight at a site (Bel Event) just outside St malo. We then set sail at 10:30 and got back to Portsmouth at 6:30 in the evening, and we stopped overnight again in Portsmouth.
The 9 hour crossing was made a lot better with perfect cross channel weather. Nobody got bored either. Plenty of food, cinema and entertainment.
We plan to use the same route year for our next French excursion.
Regards,
Pete