Static item phos painter. Moving item float tester.
Surprisingly there are relatively few open recs for "cocking about in RIBs" on Monster.com . I am guessing getting ones civ quals sorted while onboard (GCSE Maffs n Inglish), and looking hard at either going CW, RFA deckhand, going reggie to become civpol on discharge (selling soul to satan optional). Havent checked what the baseline for joining the Met is these days but probably involves some basic quals to go with your good conduct discharge. G4S hires for all kinds of roles from security to tard wrangler.
If maths n stuff isnt your bag, HGV is a lucrative route (look into resettlement early, I hear that's a sought after course), but long hours and more time away than your average matelot.
The future depends on you. The sky's the limit. If you've leant anything in the service it was adaptability. Your experience in the RN should have given you that independant outlook. Go out there with an open mind and don't take no for an answer. Good luck.