your best bet is to ask one of the instructors to help, yes they will be on a small comm, but most of them are genuine enough to point you in the correct direction. Some makes of boot fit differant types of feet and its important to get it right. Also with the new boots one pair of proper ski socks, you can even get them in m&s , is all you need.
try the hotel samakov. the shop owner helped us try the boots and made sure they fit properly, he also took the trouble to get duty free back when we left the country saving us another £50!