Welcome to Epic Alex!
There've been a few threads that have come close to answering your questions, but no direct answers to this query in the past. There was one member who went to Whistler (HET), but never reported back afterwards.
This thread talks about UK companies:
This thread talks about CSIA training:
And Canuckinstructor had this comment a while back:
You may be interested in looking at a couple of the programs like Ski le Gap (at Tremblant) or the Crystal International Academy (Lake Louise or Whistler). They run programs geared towards college age kids taking a year off to travel, etc. They have full packages with lodging, food, and several weeks of training to get your level 1 and 2. You may have something else in mind, but it's an option to look at.