We are usually traveling with our 3 year old kids. In all other area's of France we just go unprepared. Finding either a bed & breakfast or a holiday rental is relatively easy and in the summer we just go camping. This is not the case in the south of France, especially in the summer months.
I have good experiences with Google maps and Tripadvisor to secure holiday rentals ahead of time. The trick with google maps is strait forward. You first identify the area you want to go by just zooming in our out. Then type either holiday rental, self catering apartment, or gites.
There is a Dutch website aimed at parents with very small children, called petitparadis. This specific site does not have an english translation (other then the automatic Google translate), but being part of eurocamp, you can pinpoint their suggestion on their Dutch page and look for the details on the eurocamp.co.uk site. For the Riviera they suggest La Baume.
Be aware that during the summer holidays, the temperature during the day can be quite high and with lots of sun and small kids you are pinned to your apartment for the better part of the afternoon to prevent extensive sun exposure. Personally I would say that the south of France with small kids is better to visit earlier or later in the season. In hindsight I rather went to the Ardeche last summer.