We always do a trip when they go on offer in the local paper then we add the car & cabin. If you take the night crossing & sleep in a cabin its not too bad early wake up in Roscoff France then with the car you have the day to do what you like. We normally head to the supermarket before hitting the wine shops ( even Lido wine is 1/2 the price it is home in the uk). We know where we are going but a 1st timer may struggle. Then we get the night ferry back if poss, rather than a late pm sailing to maximise time. Even if you have a daytime crossing back get a cabin if you can then at least you can get your head down as its a very boring trip. I travel with my child so a chill out zone is good. Food is ok duty free isn't like it use to be but that is the same at an airport. The port at Plymouth & Roscoff run very well. If the sea is calm all well & good but if not it is rough !!!!!