Thanks Michael. I have just realised that you even have to book the tests that do on arrival at the airport in Phuket. So for anyone else who might be reading this, I think I have to book the airport test using the thailandpsas.com site and then send the booking confirmation to the hotel who will then issue a letter of confirmation covering both the hotel booking and the PCR test that I can then use to apply for my Thailand Pass. Simples....