Should I Use my Thai or British Passport to Book my return Flight to UK?

 

 

British , you will have less or no problems on arrival .

regards Worgeordie

You may have to show both to the check-in staff when you leave (to show you have right of entry to the UK and/or you've not overstayed in Thailand). 

 

Do NOT under any circumstances show both passports to immigration officers at either end. Dual citizenship causes their brains to explode!

 

You should be able to use any passport to book a flight.. But I think you will find most countries want you to leave on the same (country) passport you entered on.

I am a Naturalized Thai and when I got my citizenship, I was warned about using my old passport in Thailand. 

 

How you book your flight is irrelevant. What counts is following. 

You must leave and re-enter Thailand with your Thai passport. That means you only show your Thai passport to immigration. 

Airline staff are concerned about your UK visa. You can easily show them both passports. They can't be bothered about dual citizenship. Immigration on the other hand gives a hoot whether or not you have a visa for the country of your destination. Upon entering and leaving the UK it's exactly the same but reverse. Only show immigration the UK passport. And you may show again both passports to the airline staff. 

Above is subject that you have in both passports identical names.