RedhillPhil,
As someone in that very position within a few years of your hypothetical date I can assure you that there was NO choice involved whatsoever.
You would have been aware of the choices available to you when you were selected for the relevant OCU, and while you could indicate a preference for, say, home, Germany, Near East or Far East, you certainly could not select a particular squadron, though in the case of many types your preference would dictate the actual squadron.
In my era you were far too focused on passing the OCU, making sure that you didn't screw up and get binned, perform badly enough to go Canberra or, God forbid, V-Force!