From a general Thai forum (mostly for those married with Thai ladies in this country and thus full of people who want to go asap);
It depends-some HTL may have a direct link with some hospital and as you have to prebook they can organise that some nurse comes and do this test. or maybe the nurse comes daily at a specified time. Hence it may happen-if you arrive quite late in the day, you may have to wait till nect day for the test and have to stay there night 2 for the result
The HTL MUST collect you @ airport and deliver you without contacts-hence also without the wife or the friend-to its premises, in a MAX of 2 hrs-Pattaya is reachable, HuaHin not. And yes, they will state an all-in price for transportation+HTL+test+statement.
It remains unclear what is to happen should you fail the Thai test=are suspected to have covid
Many HTLs by now do not know how to handle it or remian unconvinced
The new THai Pass is an app that replaces all the cumbersome burocrazy paperwork that was required for the quarantine method. Thai embassies should handle this. BUT in my country they now say they are ´full/busy´ untill late nov=4 weeks ahead.
Well-known guru David Barrow(?) advises to wait and see how it works and not run for airbookings now. And I will follow this advice.
(quick math: this adds to at least 2 tests+any fees for Thai embassy+higher cost for HTL/transp etc)=I estimate at least 200 250eur.