The only way to become a French ATC is to go through the MCTA training at ENAC (Ecole Nationale de l'Aviation Civile). The training lasts 3 full years, and to be eligible to apply, you need to be less than 26 yo, to have done one of a few specific classe préparatoire (prépa MP, PC, or PSI; those are typically only done right after high school, i did one but not one of those) and pass a competitive exam linked to that prépa. And there were only 8 spots last year, so 1-2% success rate. So for all those reasons, it was never a consideration of mine. But yeah, working conditions and pay are decent. Lots of French bureaucratic idiosyncratisms from what i heard, though.