So long as you jump through the required hoops before and during your stay, you can enter on visa exemption. Dont forget you then have the British government's hoops waiting for your return!
My partner did it in December and no PCR needed for Thais before departure for entry to Thailand (though some airlines might require it). COE and F2F still required.
"A little steep"? 15 nights in a hotel - including 3 meals a day, transport to/from airport - 2 covid tests - 24 hour nurse on duty - security presence. Not a bad deal!
Thailand isn't on the "red" list at the moment, so quarantine at home is fine. Of course, this is fluid - who knows what it'll be like in a month or 2?