can anyone help with information regarding extending a 30 day visa on arrival for a U.K passport at the Nakhon Pathom immigration, is it possible to get another 30 days there for 1900 baht?

Thanks

You do not have a Visa on Arrival but you can get 30 days at Immigration. 1,900 Baht

Visa on Arrival

http://www.suvarnabhumiairport.com/en/907-visa-on-arrival

As you will note is not available to UK passport holders , only provides a 15 day stay, costs 1000 Bht and is non extendable.

What you have is a "visa exempt" entry which can be extended,once, at any immigration office for a fee of 1900Bht

Yes, you can extend your visa exempt entry as long as you haven't extended already. You will need to give an address in their area.

Ok thanks and is it for 30 days now?

Ok thanks and is it for 30 days now?

Yes

Ok thanks and is it for 30 days now?

See post number 2