UK passport, apply for Chinese visa in Thailand

Jo, you should apply for it at the CVASC in Bangkok.
It usually charges 1600 Baht. But it is just for reference. Final payment is subject to the actual amount given by the CVASC.

I regularly get a China tourist ( L ) visa at the Chiang Mai Chinese consulate . For a double entry with express same day service it is about 2950 THB . About 1000 THB less for regular 2 or3 day service . It is a small office and not too busy . The consulate is near the South West corner outside the moat .