I am flying from Don Mueang to Puket and wonder if I must take my UK passport for this internal flight or if I need nothing oir if my Thai driving license would be all I need to have with me?

Any government issued identification will do for a local flight (Foreign or local DL, WP, PP)

That said, as a foreigner you are supposed to have your passport within easy reach (some would say, on you) while travelling in case of immigration check.

But yeah you will get on the flight without any trouble.

ID is required, but not necesarrily a passport.

However, having your passport with you is best, especially when you travel outside your home town.

And if you need to checkin hotel officially passport is required.

And if you need to checkin hotel officially passport is required.

Yes, hotels are supposed to record the TM number on your immigration landing card, as well as your passport details.

You ask this unnecessary question because you are on overstay already, aren't you?

Fatfather

Sent from my phone

Why do you ask this, can you not take that decision yourself, it is after all a simple private matter.

In your local area you can carry a copy of your outlined passport page, but by travelling a long distance by car or airline it is advisable to carry your passport, which is not a security problem, nor a physical problem.