Take it from someone who has experience dealing with the Chinese Embassy anywhere....get your travel agent to process your visa for you if you are buying a ticket with them. If not, for an extra fee (normally $10-$20), they will do it for you.

For UK passport holders who are US residents, you pay the British rate. Unless you have a US passport, you are still a British citizen.

For major towns in the USA, there is a China Travel Service which might be able to help you - make sure you do not mistake them with Taiwan which sometimes lists themselves as republic of China. Mainland China is known as The People's Republic of China!