There are plenty of child friendly gite complexes in Charente Maritime (South West near La Rochelle) We are planning for next year and there are a few lovely places that are very child friendly with lots for children to do.
we went with Siblu to Lac des Reves this year and it was lovely. Great pools/play areas and kids clubs. The village was within walking distance, and 5/10 mins drive to larger resort places and the beach.
My daughter saw an advert for a family friendly villa in the South of France on the Small Ads section and we have been 3 years in a row now. we've been back every year because we want something where there is more than just a beach and the Languedoc has lots of stuff for us to all enjoy. we go with our daughter son in law and ourgrandchildren and we all love it. we have been to Spain and Portugal but have all fallen in love with this part of France and the villa too. the children almost feel like its our's as we've been so often. Our other daughter has joined us too a couple of times. the website is www.villakarli.co.uk/. oh and I think you can get a discount for being a mumsnet member so its worth asking. happy to answer any questions if you want to know anything or else you can contact the owners as they have always been most helpful to us. hope this helps
Try looking at some of the websites where you can book direct with the owners e.g. holiday-rentals.co.uk or ownersdirect. Tots to France personally inspect all the villas that they advertise so if baby/toddler friendly is a priority they might be worth a look.
We have a villa that meets your requirements exactly but it sleeps 11 + 2 cots so may be too big for you.
The Languedoc tends to be cheaper than Provence and less touristy but the scenery is different so it really depends what you want.