What are the steps and options for getting a COVID-19 test in Bangkok before returning to the UK?

An expat in Thailand is seeking information on the process of returning to the UK, specifically regarding COVID-19 testing requirements. They plan to fly directly to London with Thai Airways to bypass hotel quarantine and mentioned the need for a Passenger Locator Form and a COVID-19 test within 72 hours of departure. Various commenters provided recommendations for clinics in Bangkok for testing, including MedConsult Clinic and Bumrungrad Hospital, with some sharing their experiences and the need for pre-booked tests upon entering the UK.