I cannot believe after reading so many posts on here that, after doing a week self-isolation following the Phuket Sandbox, it dawned on me Wednesday night that I have to submit a TM30.
I got copies of all the documents I need printed today so it's off to Sa Kaeo immigration on Monday to file it and see if I get the 1600B fine.
While I'm there I'll get the TM7 for my extension and find out what I need to provide.
Update - TM30 filed and no 1600B fine. Arrived 10am and walking away at 10.08 with my TM7 for my extension towards the end of the month.