Proof that i am not a British National

Hi everyone

i currently live in hk and am applying to be a CHinese national here. The immigration department has requested me to get proof from the british consulate stating that i am not a british national. Im guessing this is due to the fact that there are many people who choose to hide it. I contacted the british consulate here and they said only the home office can do so. The woman on the line gave me 2 forms that could help. NS and NQ, however doing more research into the forms they seem to be for people who live or have lived in the UK before.

To clarify, I've never lived in the UK nor do I hold a british citizenship. Pretty confused on which form to fill out. I want to make sure its the right one as the fees are pretty high.

Would anyone here have any idea?

Thank you!!