I've been to Ray at Grahams, he does a really good job. Lots of people have been saying this for years.
I've been to Derek (now at Studio AV), he does a good if not better job. I found him more passionate and meticulous.
Last time I went to Peter at Cymbiosis in Leicester for a rebuild and it was like adding 60% more KEEL. I was gobsmacked. And I'm not going anywhere else in the future. It is worth the several hours in the car.
Closer to your home is Ultimate Home Entertainment Solutions in Painswick, Gloucestershire. I've visited (not with LP12) on the way to visiting a friend in Ebbw Vale, I liked UHES a lot and I've also heard very good things about their LP12 rebuilding skills. Apparently the guy that runs it has known Ivor for about 40 years.