if in UK bitcoin is already regulated, logic is telling me that you should simply follow the normal rule for any shop that you want to build and that would accept fiat
it shouldn't be much different with bitcoin
Pretty accurate, imo.
If you call HMRC's AML unit based in Southend-on-Sea, they will tell you what you need to know. They are very helpful.
You'll probably have to apply to be regulated by the FCA as a money services business, but also apply to HMRC's AML unit for AML regulatory licensing.
FCA will check you are capable of running a money services business, HMRC will ensure you comply with AML.
https://www.gov.uk/government/organisations/hm-revenue-customs/contact/money-laundering