Expect the phone lines to be VERY busy. Check their website or Facebook page first, they should have notices posted about how to go about getting this done.
You would have to use your Thai passport. My wife flew from London yesterday and the person she was travelling with had both Thai and UK passports. She was told at check in she had to use the Thai one.
Plus, you would need the additional documentation that is currently required; A Fit to Fly letter from a doctor, and a letter from a Thai embassy or consulate confirming that they have approved the journey. Both of which need to be issued less than 72 hours before departure.
For details on how to do that, contact your local Thai embassy.
I'm not the person to ask about that really. I was at the Thai embassy in London today and they didn't know much about it either. There's a form that you need to get signed by a doctor
Your best bet is to ask the airline as they are the ones dealing with the requirements sent to them from CAAT so there wouldn't be much point standing at the check in desk saying "But Biff said it would be fine"
that’s not what it says in the Thai section of the photo. It says they have to get a ‘fit for travel’ certificate from a doctor and have it stamped at the Thai embassy before they travel. Not quite as difficult as the requirements for uk nationals, but still something they have to do. Also the Thai embassy said they will have staff at the airport to provide the stamps for a few days.