@Andrew *****
Okay, that’s a strict embassy. If you want an approved health insurance, you’ll either have to choose a company from the list or apply to have another one approved using the form from the attached link.
Then you need to book your ticket with a return flight if that suits you. Otherwise, you can just get a cheap throwaway ticket out of Thailand.
You’ll also need to include the booking. If you don’t want to book much of your stay now, you can use a hotel service that allows free cancellation after the booking has been confirmed.
*****************************************************
***
pRkP4tkCe/Form(s)/ENG/แบบฟอร์มใหม่_(2)_Foreign_Insurance_Certificate_1.pdf