You could base yourselves around Caen or Bayeux .. the Bayeux Tapestry could be of intererst to your daughter, and there are plenty of play parks and the seaside too. You could visit Honfleur, try the local cider and Calvados, enjoy Camembert cheese and visit a working farm (Percherons are large Normandy carthorses).

Then of course, Mont St Michel is reachable too, also major shopping centres like Caen, Bayeux and Arromanches ..........

Try Googling Office de Tourisme de Caen; same for Bayeux and also Office Departemental du Tourisme de Normandie for starters. The French children will be back at school after the first week in September.

We found the Caen Memorial to be very child friendly (we had a 21 month old with us when we went) but it would also appeal to your dad.

Mont Saint Michel is 4 hours Autoroute driving from Eurotunnel
that gives you an idea of range Oh btw it's 8 hours via RN roads

Keeping kids amused is not my strong point but there's lots of places to go and see around there and whilst the Mount is busy busy busy it's got some great things to find especially the interactive museums for the kids

and you will have Cidre farms to visit - at present a champagne style bottle of Nomandie Cidre is 1€ (2 % or 5% alcohol)

and as for booze cruise forget the Channel towns and the Citie de Europe the Supermarche and Hypermarche are cheaper the further from the docks you go

We NEVER buy brands that are available in the UK in France (so Tesco misses out ripping us off) and usually find some extremely palatable wine for prices that are unimaginable in the UK

You will have a problem not overloading the car so suggest you get a trailer you'l need it