Dominique
Don’t worry about getting gear here in France. As Rick mentioned, Thomann based in Germany provides a global service but also delivers to all EU countries at a reasonable cost.
I’ve bought most of my gear from them, to much too list here so a review of my Road Case aka now Learning Log may be better. HERE
Bar my Squier Affinity Strat, Encore acoustic and Washburn HB30, everything else was bought there - well not the Jack D Cigar Box, that came from the manufacturer in Italy !!
Apart from the voltage differences I doubt your amp would sound any different with the right power adapter. But I would think it better to buy something that runs on 220V by default. However I did think my old Marshal Goldline (orig UK 240V) had a little accent Francaise when I used it here 
kidding. Both Marshal and Behringer GX110 worked fine when I moved over from the UK !
Depending where you are going to be based, there are some decent music/guitar shops over here. So you could always search for something local. Having said that apart from guitar purchase I sourced a Fender Mustang III and a Line 6 POD Go from Thomann.
They also have a 30 day cash back returns process, if you are not happy with your purchase, Plus a good guarantee service. The 6 way switch on my Roadhouse Strat when on the blink after 10 months. They arranged the back shipment gratis, fixed the problem and sent the Strat back all within 2 or 3 weeks. Happy customer here.
Good luck on the move btw the way. Its a great place to live !
