In order to close a bank account in the UK, I need to submit a notarized copy of my passport. My nearest big town is Prachuap Khiri Khan, and I would be grateful if anyone could recommend an office that will do this. I looked on the internet, but found nothing. With thanks.

The reason you found nothing is that Thailand is not a signatory of the agreement so no international notary service is available outside of some Embassies providing.  That said there is a Thai system that is often accepted but no guarantee and many lawyers can provide. 

Perhaps be easier to just withdraw funds and let Bank worry about closing? 

As stated, would think your embassy is your best bet.

 

There is a 'ministry of ???' at Krung Thep that notarizes statements for foreigners to marry Thais, but would be more hassle, and possibly expense vs your embassy doing.

Thanks to both of you. I looked at the British Embassy website and I see that they charge only 25 pounds for the service, so I will go there the next time I am in Bangkok as this is not an urgent matter.