Bring along as much proof of training as you can, and record of authorizations for work on equipment.These will help your assessment for the cert IV, you may have to do a bridging course to cover any perceived gaps. I had to do similar stuff, and that was from RAAF training go figure. At least i didnt have to go back to school. We have had uk exchange programs in the past (defence that is) so shouldnt be too hard.
Good luck for the future.