There is a restaurant on the site, and some entertainment - but the area where the tents/vans are is quiet at night. You're not allowed to take your car on to the site if you arrive home after 11pm.
It's really safe for kids and we had no qualms about allowing ours to run around on their own with other kids they'd met there - they were about 7 or 8 at the time. The gang would rove from one tent to another cleaning each out of crisps, nuts, biscuits etc as they went!They also hired bikes from the site office on occasional days, for use on the site only.
The pool area on the campsite is also good, and there are organised children's activities.
There is LOADS to do in the area. Lots of pre-historic sites where people used to live - you can visit ancient cave dwellings etc. and the cave paintings at Lascaux are not far away. Lots of pretty villages, and local markets.
We went to Rocamadour from there - that's a really pretty village on the edge of a cliff. And there is Le Parc des Singes, where you can feed "wild" monkeys, which your kids will love.
There's a brilliant cave called Le Gouffre de Padirac, where you can go on a boat on an underground river.
Five and a half is fine for canoeing - they give you life jackets, and the river is pretty shallow for most of the way. You can stop lots for picnicing and stretching legs along the route.
I would highly recommend that site.