garage door insulation

Hi all, I'm looking to convert my new garage intk additional room used for working in. It's single skin detached with a pitched roof newly built (if that makes a difference). Obviously I want to make this into a normal room adequately insulated and holds of the mould that seems to appear after...

I have a garage door here - its a roller type door. I've sealed most of the draughts - whats the best way to insulate the door itself, as it is not insulated. Any recommendations? (See images below) Image 1: https://1drv.ms/i/s!AvxDFgUHUgNC1kcDmGWmLEpV_hsw Image 2...