Hi mate, have a look not just locally at your independent companies but outside the box a bit. I work at a government funded laboratory as a pipe welders mate (was a chief engineer in the navy, then offshore oil and gas and a property developer, then an electrician!! ) and a rival company takes on anyone with ANY pipe related experience. They do gas safe stuff, domestic plumbing, commercial plumbing, coshh lines /extraction, HVAC and they are all over our site as it is a progressive research site so always plenty to do !!!
Don't corner yourself in a market that is much wider than people think and also includes the Army (they have plumbers), domestic , commercial, piping services and HVAC. You have valuable skills mate and it is a great time to be getting stuck in !! A buddy of mine started with Turner the estate services guys as a Pb mate and he is now always on call, works weekends, gets loads of overtime and great flexi time perks etc so cast your net wide (and abroad!).
Best of luck mate