I spoke last night with the Air Cadet officer who is responsible for the cadets at St. Andrews. He advises that both Harv's locations have facilities to billet students, and that both facilities are fully booked with Air Cadets in July. This summer only female Air Cadets will be using St. Andrews.
The Steinback airport has only one runway, whereas the St. Andrews airport not only has three runways, but is in a positive control zone, with an ATC tower. There obviously is some benefit to training at a controlled airport, and with three runways, the chances of crosswind limits for ab initio training being exceeded are very low.