What is the process for changing your last name in Thailand for a UK citizen married to a Thai national?

Go to a district office with your partner. Show them the marriage certificate and say you want to change your last name. That's it.

I am a US citizen, my Thai fiancé (at the time) did all the work without my help to get passport and complete all the steps to get her fiancé visa. We went to US, married and then I changed my last name to her’s. I started at the driver’s license office and they pushed back hard. I simply stated that if they don’t help me then I will pursue discrimination based on gender. After a 3 minute huddle in the back office, they changed my last name. Then off to Social Security office to do the same. Then notify credit cards, banks and all.

Good luck. It helps to be knowledgeable, correct and assertive.

I under you are doing it in Thailand and I did it in USA, but I am hopeful my experience will give you the wings you need to fly.

I dont know the answer to that particular question but you probably qualify to apply for Thai citizenship.

Also i believe the answer to your question is on website. Follows the linnks Thai citizenship group

When I got married my Thai wife had her name change document done at the same time at the local Amphur who then also issued her new ID card. All very simple, at least it is in the Amphur where the marriage is registered..