The black roof lining is only available for models with a sunroof, so if you don't have one you're out of luck
Headlining is held on with clips and all the interior trim, handles, sunvisors etc. Its also glued on arround the runroof opening, some care is needed here to make sure you dont rip it whilst you remove/refit.
One thing to remember, is the 3 door B pillar trims (behind the doors) are held in with clips, once the seatbelts & levers are removed push the trim UP towards the ceiling to release it
The C pillar trims are clipped to the car and just pull off, as is the trim along the roof by the tailgate. You'll need to remove the parcel shelfs to get the c pillars off, which is a good plan cos then you can replace em with black GTI shelves at the same time :) While you're there get the boot side carpets as well, it cleans up the boot no end with em fitted!
Edit: If you are planning to fit one, I'd remove the old one first before you go to collect the replacement, its VERY fragile once out of the car! Theres a 3 door MK2s with the black headlining in my local scrappy down in Wokingham, but you'll need to come and get it
