my 10yr old was in lessons and i was suprised that there were no helmets, we were not told if any were available either.come to think of it i did'nt see any kids with them on.
If you cant get hold of either snowshack or interski by email - pop in on your first day and either will be able to help you - As Pete said they are both under Markony, at ski centre 2. I dont know the hire costs for a week, but sure its not a lot.