You could use Helen Dart from Bookham Saddlery, or Pippa Bassett from Broomells 01306 711514. Pippa is good and very reasonably priced. She is also very fast. helen will charge you more, but she does know what she is talking about, just don't let her talk you into spending money on something new.
Don't use Spragg no matter other folk say, not a massive fan of Buttons fitter either though I have heard good things so think my experience was a one off.
Adrian Benge from Buttons does a good job IMHO. He's not 'just a fitter' but co-owner & master saddler (and has been for many years)
He's also crown appointed too, so does all HM's saddlery.
Helen Dart at Bookham Saddlery would be the one I trust most. Have heard mixed things about Buttons and not had a great experience with them myself but that was years ago.