Been there but unfortunately not in windy season. July should be good. Apparently they test a lot of kites there in August. Le Morne is the place where everyone goes (and all the pictures are taken) but apparently there are several spots all round the island that are great too. Le Morne is a relatively isolated area of Mauritius on the bottom left hand corner of the map. Only four or so resorts in the area (not exactly cheap). Indian resort (kite school attached) is the kite out front option at Le Morne.

This website might be helpful www.mauritiusurf.com/ for spots

Yeh, Le Morne is definitely the spot. I was there two years ago in April, and stayed at the Indian Resort. I was there five days and kited four. Plenty of options for kiting, with the lagoon providing flat water and of course "One Eye" which is a fast and scary reef break if your game- I wasn't. July should be perfect!! I'd recommend the Indian Resort. Great selection of food and comfortable accomodation. It's probably the most reasonable resort in the area.