I asked this question and apparently they wouldn't have contacted me. So never is the answer.
Its not a problem now I have a lifetime licence but the thing that annoys me is that the DVLA manage to send out tax reminders for over 30 million cars each year without fail.
Yet the CAA can't send licence renewal letters to the 20k or so UK PPL pilots that are out there.
Very unprofessional and very, very annoying.