On paper I have 1 share in my company. How can I sell a smaller percentage of my company to another party?

How do I sell paper shares?

Certificated share dealing accounts allow you to sell paper share certificates.
How to sell your shares online

1. Complete an application confirming your personal details.
2. Share the information on your certificate as proof of ownership.
3. Send your certificate and printed application to the broker to confirm the sale.