I've spent a lot of time in the area because my parents had a house near Montreuil-sur-Mer (it was 'on Sea' until a couple of centuries ago). The countryside of the 7 Valleys is beautiful and there are some fabulous beaches and dunes on that coastline.
I love the beach and the indoor market at Le Touquet. And there's Parc Bagatelle nearby, I've never been but my parents have taken grandchildren a few times over the years and all enjoyed it.
Berck sur Mer is a nice seaside resort. Be aware, the beaches on that coast really are HUGE. You can walk for miles across the sand just for a paddle.
Montreuil is nice for a wander and if you're there around Bastille Day on 14th July you can catch a performance of the Son et Lumiere at the citadel. It's...an experience.
Also De Panne in Belgium isnt far to drive once youre over the channel, and thats a really really lovely seaside town that do amazing crepes and gaufres. Theyve also got an excellent child friendly attraction park called plopsaland, www.plopsa.be/en
we took ds1 a few years back, and this has just reminded me that i really want to take the other dcs too
northern france is really lovely in its own right. Its still usually a few degrees warmer than southern england in the summer, although obviously not as hot as the south, and there some amazing white sandy beaches. Theres a lot to be said for not having to drive too far, and ofc not everyone appreciates the heat of the south in the summer. It was still hot enough last summer though and we swam in the sea and sunbathed etc, and while the beaches still get busy at times, it was nothing like as crowded as the english beaches in the summer, as i think so many people just head south. Much more practical for the children
We went to Nausicaa at bolougne sur mer last year and the kids loved it. They have actual sharks!
We stayed at Chateau Drancourt as part of a MN Keycamp comp prize . Free caravan accommodation for a week - it was fab! Great area - we enjoyed St Valery, and the wonderful bird reserve on the other side of the estuary (saw storks nesting - v impressive) and a trip to some underground caves at Naours. A lovely visit to Montreuil-Not-On-Sea!
If you do stay, be careful where you pitch. We were allocated a stony grotty pitch at first but went back to the reception having found an empty one we liked, and they were really helpful and changed us over immediately.
There is a pool area - it has a covered pool and an uncovered one, as well as a small baby pool - and a small children's playground. Nothing amazing but our then 2 year old was quite happy.
We didn't try the restaurant which may be lovely. The take away pizzas weren't though. I would avoid them.
It is about an hour's drive from Boulogne I think and is within easy reach of Le Touquet which is lovely to visit.
That one looks good, Porto - I like a campsite on a beach.
I gave driven past the entrance to one which looks as if it is on the dunes in one of theose coastal villages either side of Wimereax - maybe near Audreselles? (sp?) I should have stopped and hot details - that would be a fabulous stretch of coast to camp on, lovely seaside places, Wissant etc.
The coast S of Le Touquet, between le Touquet and St Valery is lovely, too.
I know that area quite well, but have never camped.
It is a shame people go straight past it, as it is beautiful - if you google Vallee de la Course, you'll get lots of info about the prettiest bits. I'd go near Montreuil sur Mer (it isn't that near the sea) and Le Touquet. There is loads to do in Le Touquet, including Aqualud if your DC like swimming, and there are cycle lanes all over the whole town. Nausicaa in Boulougne is also quite good, but better for slightly older kids I'd say.
Wimereux is another of my favourite seaside towns, and it only takes about 20 minutes to get there off the Shuttle.
I could go on and on about this all day - I live near the channel, so lots of day trips and holidays over there ever since I was a child!
We spent a few days in Bray Dunes last year,Not camping, but its maybe 45 mins-ish drive from calais iirc. Beautiful huge sandy beach and lovely shallow waters for children. Also nice little town in the summer with a few amusements etc and playparks for the children, although we mainly stayed on the beach and walked in the dunes. They go on for miles. There seems to be a couple of nice looking campsites in the area. You can walk up the beach to dunkerque