ya on the way back you should take advantage of our cheap fuel (43p at mo) caus its going up by the week. St malo if you go you can lock on to the main marina and you will be right by the main town. dinard is good but limited going up the rance is brill been many times, if you are following the gulf of st malo north to south there are 4/5 good stops one quite one called delleit another Cartrette, portbail antother quite but very nice town then realy the last one is granville this is quite large, when you get there paimpol is also verynice depening how far you want to go there is plenty of marinas to go to east of st malo. hope this is some help.
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