UK bank statement, flight to Thailand, flight out of Thailand within 60 days, passport photograph, colour copy of passport. Application can be made 9am to 10am Monday to Friday.
We're retired and have income etc. but I only turn 50 in May, so we were just trying to get to stay until then. I had all the insurance and documents to apply for Non O if we were to be allowed back in. Personally, I think the admission of guilt was the deciding factor but who knows. The last thing the officer said was that she understood our situation but please only use correct visa in future.
We were well prepared for that with supporting documents and were prepared to be denied as well, as we'd been here over 2 years using a tourist visa, a 'visa that shouldn't be mentioned' plus 2 x covid. The signs above the interrogation officer saying "lie to officer, 6 months jail" is quite unsettling. We'd pre-agreed to be honest and apologise for using wrong visa. Worked for us anyway.
Also, the problem isn't getting the visa, it's getting through Thai immigration. We were grilled separately and together for over an hour in the detention area on arrival.