Yep,you can either opt to pay tax to the UK tax office or to that of China. However,if you choose the former,I advise you to make sure you are totally aware of the regulations that would affect you.UK tax inspectors are sticklers for detail.So,for example,you should find out exactly how many days you would have to be outside your homeland per calendar year in order to qualify for exemption from UK tax,should you decide to go down that path.I'm sure your bank can give you detailed information re that.
As for the employment regulations for foreigners in China,so far they have not been applied throughout the country.Not only that,but Beijing 2008 showed us they can be subject to sudden and unexpected change,just like British weather!
Good luck with your tax avoidance.Long may it continue!