I don’t know where you are in the UK, but I would recommend a place local to me, Adams Watch Specialist in Aberdeen.
https://www.adamswatchspecialist.co.uk/
Nick Adams recently installed a new movement in my Scurfa Diver One, after I killed the original while attempting a battery change at home.
I was very pleased by the service I received. The work was completed within a week and they were able to pressure test the watch to its 500m depth rating.
Hope this helps!
David