How Can I Obtain WP3 for a Business Visa Application in Thailand?

Hi all,

I am trying to apply for a business visa (non-immigrant B) as I have a job offer in Thailand. My employer has sent though an invitation letter and various supporting documents including their business license and financial records. I am a UK citizen.

The London Thai Embassy website says I have to use the online application system. There are two questions that I can't answer and the system will not let me proceed without uploading something for them - please see screenshot.

Document 8 is a WP3 which I don't have. How do I get a WP3 ?

Also the website asks for a "confirmation of legal residence in the UK (Document 9) in case you are not a national of the UK". I am a UK citizen and have already provided my passport details, but I can't see a way of giving this answer

Also I have read elsewhere that I need to provide my health insurance details but there is no facility to upload them.

Any tips? Thanks in advance