Update - went to do my name thing today.
Important point - take your 5K receipt as you need that for some reason. 1 hour wasted there driving home and back for that.
Picking a name is tricky, as you cannot choose an existing surname for fraud reasons, nor something that sounds silly or unThai. Basically it is like trying to guess what someone else is thinking, in a language you can't speak very well. They gave me a book of potential names, but as it was old all, the ones my wife chose were taken. I suggested the name of 1 of my favourite Thai golfers, and the lady behind the desk checked a slight derivative of that, which past the 1 factual and 2 opinion tests, so we got it done.
I have now done everything required in the envelopes (feels a bit like the Crystal Maze) and await whatever's next.