Taffy,
Sorry I can't help with any first-hand info on the campsite but try their webisite: www.camping-le-mas.com/en/emplacements.php
I do know the area very well having been visiting there for work and vacations for over 20 years - am thoroughly envious of your plans. Camped in Sausset les Pins many years ago and had a great time - the Cote Blue is the real Provence in my opinion. Martigues is very picturesque - please check out Le Brasero a small restaurant on the unpopular side of the main drag - Alex and Blandine the hosts will make you very welcome and are happy to speak English, if your French isn't up to much.
Hope your plans work out.