A ski host is not a guide - you will 100% get into trouble if you start calling yourself a guide.
A ski host shows a chalet companies guests around the piste. They stop for lunch, and talk about the best places to eat a fondue.
There were some problems last year, as the French saw ski hosts as 'guides' who were taking away business from the ESF. As long as you do not wear a uniform, look like you are teaching a group, stay on piste and pretend that you are simply skiing with a bunch of friends, you will be fine.
If you really wan't to be a guide, I believe you'll need to do your BASI 3 or 4 to meet the equivalent French standard, and your British Mountain Guide qualification to guide on glaciers. I'd double check this though - Google. Either way, to become a 'guide' in the sense that you are operating legally will take a good few years, and cost a lot of money.
My advice for doing a season - fuck off working for a chalet company/tour operator, sort out your own accom in a resort of your choosing, arrive early and find a job paying cash. Otherwise you will end up being a bitch all winter and have little time to ski.
Sources: 7 winters in the alps