If you don't get any interest, then don't let that put you off, just try it on your own - after reading one or two first-timers' stories then you may have more confidence. There are several good posts on other camping/caravanning forums.
Towing in France is easier, there are thousands of campsites, and on many you won't need to book, the service areas on the autoroutes are caravan friendly, and even on the N roads you may find picnic areas with tables and chairs, room for car and caravan and sometimes a toilet block.
If you want to go during the summer holidays, but pay a bit less, and find less crowded sites, then try to go after the 15th August - campsites tend to quiten down then, and prices come down on some sites. You can also use things like
Camping Cheques,
Touring Cheques, or an
ACSI card which means a night on site will cost between 11 euros and 15 euros, depending on which you use. That covers two people, car and caravan, awning and electricity, and then you pay a supplement for each child, depending on their age. If you don't want to go too far there are plenty of sites in northern France. I have a spreadsheet of those sites which accept Camping Cheques or Touring Cheques during school holidays - if you'd like a copy then email me and I'd be happy to send it on.