Hi Ben,
This is a really hard one, as I also found it hard to find a local garage that I trusted to work on/service/MoT mine. I was transporting mine down to Middle Barton Garage in Oxfordshire, which wasn't practical at all.
I've found one now, but I'm down near(ish) to Worcester, so no good for you.
Tom (Hobbler on the forum) lives near to Chester. He's a very, very knowledgeable owner, and might have some tips for you if you message him directly.
Failing that, if you can find a good, local classic car group they could at least point you in the right direction of a garage/mechanic that understands classics more broadly.
Good luck!