Reading all replies, and most importantly your thoughts Paragon, the A320 route ticks more boxes and has more plusses than negatives. The next few years are going to be hard for everyone in the industry. Being a captain at a small operator with an "uncertain" future is perhaps the riskier option right now. With an A320 rating there will be regular opportunities to get back to the UK in the future. Turning down a command opportunity is hard, I did it last year, at the same stage of career as you, to join the bottom of the list at BA. I get the occasional twinge of regret but as someone else pointed out, whatever you decide looking back is pointless, the future is far more interesting.
Good luck!