I am pretty sure you can get a document showing you have recovered from covid and are not contagious anymore and have natural immunity (if from U.K., it’s on the NHS app) and can use that. Confirm with Thai embassy.
Sounds like you didn’t book the test and go package, including airport transfer and test. Look at your hotel confirmation, it should tell you exactly what you booked. Your hotel should also have contacted you for details of your insurance and flight booking, so they know when to pick you up. You can find a cheaper SHA than 170 euros, maybe just rebook an SHA… lowest approx
staying with family or friends. I can just go to immigration with the address and pick up a TM30 (the top pic) myself, right? Within 24 hours of course.