Mary and Alice appear in the British pavilion regularly, but they come "onstage" through a door behind the IG shop and walk over to their meeting spot. So you might see them in the area, but they aren't part of the "character training" initiative.
Gaston was the latest "in training" I saw when I was there for the F&W festival, I also saw Ariel and Rapunzel in that area (separately, not together). Couple of years ago, had the great fortune to run across Captain Jack Sparrow with nobody lined up to meet him.