Thanks everyone for your comments
A carpet pole is the cardboard tube inside a new rolled up carpet with a diameter of about 5" a bit like a Huge toilet roll tube. They are very light and flexible and easy to work with.
I had the sun visors re trimmed by my local auto trimmer, he also made the headlining for me too.
I have searched on trim and seals sites like
www.sealsdirect.co.uk for a J profile trim to tuck under the screen and over the edge of the headlining buy they don't seem to make one. I have decided to buy a large U profile and remove one side with s sharp blade and thus create a J profile. It will require a good coat of impact adhesive so it sticks first time.