Thanks for all the replies - you ace people! We are heading to quite near Beziers - we have done that journey twice before but that was before the little one when we weren't so obsessed with sleep (ours & hers ;-) and it was pretty full on then, so I do think a stopover is a must, jsut gonna work out the timings etc etc. Thanks for all the top tips. Enjoy the sunshine if you've got it....
I would definitely stop - particularly if going to Riviera as traffic can be much heavier and toll queues longer. Languedoc is a bit easier. I have done the trip lots of times and we always stop over Macon/Lyon area off the A6. We make it part of the holiday. You never know if there is going to be an accident etc. We spent hours on the motorway at Valenciennes one year. Novotels are usually excellent for kids - play areas and pools and free breakfasts. Macon Sud and Lyon Nord are both good. And one year we stayed here just off the motorway at Macon Sud. It was lovely with free wine tasting, nice food and breakfast served in the garden.
If it is an 11 hour drive from Calais, and you only have one driver, I would go for a stop.
We do a mad crossing sometimes - Newhaven - Dieppe gets in about 3am, and then we drive until we get there - about 9 hours. DH drives to south of Paris (I sleep), then I take over and he sleeps. We both feel a bit crap. Boys hopefully (usually) behave!
I have seen someone collapse on the ferry after a night drive. He looked fit but knackered.
FWIW, this time we are crossing Friday night, driving about 2 hours, stopping, and then will have 6 hours drive the next day. The boys have always been good travellers so we are pretty lucky.
We are planning a trip to South of France (from London, ferry from Dover) in Sept with our 22 month old (she will be almost 2 by then) and debating what the best time to travel is... only 1 driver (hubby) and its an approx 11hr drive once accross the channel, but he would prefer to do it overnight, whilst I think that's possibly madness and we need a proper stopover rather than just breaks. Either way will be hellish I think, but I wonder if any of you have done this journey and have top tips???