I've managed to register on the new TM30 website at https://tm30.immigration.go.th/tm30/#/login and submit a TM30. The docs I uploaded to register were my wife's ID card, blue house book and my passport ID page. After submitting my registration I was sent an email which I had to reply to to confirm my email address was correct. After I confirmed my email, I was sent another email approving my registration and a username and password. When logging in for the first time, you are forced to change your password. I then continued and added details of the house etc. Then I submitted a TM30. All seemed to work OK.
I used Edge browser because Brave did not show the Captcha and I didn't want to mess with Brave browser settings.