Are Hua Hin Immigration  currently issuing up to 30 days extension to visa exempt entries? UK passport.

Yes 

You can go to the immigration service point at BluPort Mall for that, instead of making the trek to the main immigration office that is in a much more inconvenient location. 

Thank you gentlemen. Recently, the Bluport Office would extend only five days and were referring applicants to the main office for longer extensions.