We know that you don't need to be told what to pack for a skiing course, but here are few things you might overlook.
REALLY IMPORTANT to remember apart from obvious items like passports-
EHIC (European Health Insurance Card). Check the expiry date. Renewals are free from the DWP. Don't order from commercial sites - they will charge you!
Top up health insurance. Many people don't know that the EHIC only covers about 70% of emergency treatment in France.
Carte Neige insurance. You can buy this with your lift pass and it is very cheap. If you get carted off the mountain, the pisteur service like to see it as proof of insurance, but it covers ski accidents only, so if you slip on ice in the street and hurt yourself, it won't cover that, hence the above advice. Carry all the above stuff with your lift pass.
Mobile phone with SOS numbers on your contacts list ie Piste patrol & public ambulance .