@Mark1340 The nationality of a guest isn't the issue- it's where they are coming from, what their plans are when at your listing, and whether they take serious precautions. Just because a guest is Chinese, and has China listed on his profile as his location doesn't mean he hasn't been living in the UK for the last 2 years.
I have a home share listing and haven't hosted since early March. Don't anticipate being able to host for the foreseeable future until the virus is no longer a threat. Simply not worth the risk. There's other ways to make money without risking your health and your life.
You have an entire cottage listing, I see, so if a guest intended to self-isolate and was as concerned about not spreading or contracting the virus as you are, it's probably not a danger, but we have no guarantee that a guest will behave responsibly even if they say they will.