Thanks to everyone for the replies, really appreciate you taking the time to do so.
I think my main concern is getting a CCJ so rather than just disappearing I think I will notify the banks that I am no longer living in the UK. Does anyone know what my obligations are? Do I just need to tell them I am permanent resident outside of the UK or do I need to give a forwarding address? If they did pursue a CCJ in my absence and used last known address in UK then I tried to get it set aside, would I be refused as I didn't give them a forwarding address?