Hi Rich, for an armourer you will need to head over to the UK Garrison https://www.ukgarrison.co.uk/forum/ You'll need to do this to get clearance, as you Live in Wales you'd fall under our jurisdiction. The team over there will help get you up and running.
For other questions please do feel free to hang around, and once you've done your initial clearance please check out our level 2 (Expert Infantry) and 3 (Centurion) clearance programs.