I had the same struggle here (Colchester) when trying to find a breeder. The closest one was tuftyfluff, which was still almost two hours away, and she was in hospital at the time. I have seen since then that she has made a full recovery and back to work now thankfully, but I don’t suppose much help for you being so far away!
Also I understand the struggle with finding appropriate secondhand cages, they are far and inbetween so I understand how making one may end up being simpler. I was lucky to have found Mitzi, I found her on preloved after children got bored of her. But I haven’t seen many female hamsters for adoption after her so I know it can be luck sometimes.
Happy to hear you’ve got a bigger room! I’m sure whichever hammie you get will be very thankful. You’ve probably looked at all these but check preloved, pets4homes, freeads, also a uk adoption page:
Hamster Foster and Rescue UK
I think also here do all over the UK:
Happy Hamsters UK - Home
PS hams is in Somerset and 48 minutes from Devon, here is the rest of the list of southern hamster club:
SHC Breeders – Southern Hamster Club
I’m sure there’s others on there that aren’t a world away but I don’t know Devon area that well. I did have a quick look because sometimes you can have ethical breeders who have certificates but aren’t registered with the hamster club. I just found one called Lilac dream hamstery in Devon:
Waiting List Application - LILAC DREAMS HAMSTERY
It doesn’t have much about awards, I think she is a student of sorts but promotes ethical breeding. Maybe if you could ask where she originally got the hamsters from (as they normally start from another ethical breeder) and just ask some questions. It seems better than ones on preloved at least so it’s worth a look. Hopefully something I’ve said helped somewhat!
From your first message I presume you may have even found one but if not something here should help