Sorry ....If you tell the holiday company when you book it should be no prob... I'm size 11 in skiboots and there are bigger sizes at the depot than that..
This depends who you book through, Balkan state in their brochure if over size 11 you may need to take your own, a get out clause if ever i saw one, though as other posts have said there are bigger sizes available, Inghams have no restriction, just let your company know and should not be a problem