Not that simple, Mike.
Where are you based?
Where is your employer based (UK-arm of Chinese company)?
Where is your pay going (into which country)?
Depending on thre answers, you are very likely to be an employee of the company and not self-employed. Maybe that wasn't your question?
You don't have a choice about your employment status - HMRC will decide on it for you. Suggest you may need to talk to them about your situation.
Do you appreciate the difference between a 'contract of service' and a 'contract for services'. The first means you are employed, the second means you are self-employed. Google it if don't then feel free to ask more questions.