The visit to a FSDO ceased some time ago and applicants must go to a DPE. As the DPE is limited to two licensing events per day and signing your paperwork counts as one event, you can expect to pay for the privilege as reported by matthew. That is not likely to change post Covid. Perhaps the easiest way is to line up a DPE, then when you get the chance to make a visit you can complete the paperwork and then arrange to see your chosen DPE on arrival. Not aware that there are any DPEs in the UK, might be worth contacting one of the FAA CFIs in the UK as they may have contacts.