Hi, and welcome to the forum.
Easiest way to find English language programs in Nice is to go to the online yellow pages
Meta redirect code and put in "cours d'anglais" for "Quoi, qui?" and "Nice" for "Oł" and see what you get.
A quick look through what I got with that search includes Berlitz and the Wall St. Institute, which is a franchise operation that is advertised all over France.
Cheers,
Bev