"A paint and a dye is to me vastly different, but will obviously accept that you done the right thing in this respect. It is small white marks on the door cards that made me want to obtain some form of touch-up, otherwise the interior is good. However, again it may be what I have got used to and needs renovation.
The seats, are they leather or plastic? As know it is the driver's seat that suffers the most. Would the same paint be ideal for this job? "

Yes, stain to me is a very low viscosity, like water, but the product from Leather Works is thicker like a paint. It works really well as mine has been on the leather of the seats and the steering wheel for at least ten years and I couldn't go back and find the exact spots I touched up as it blended in and looks like original. The bolster side of the seats are leather the seat center is vinyl. Thing is the color you get probably won't be exact. You will need to work with the toner to get it just right to match your interior. Not all that difficult; Just be patient and persistent so don't be in a hurry. As far as using it on the vinyl I suppose you can. It should work fine.

"Are their products available in the UK" Go to their websites and check shipping. I don't know. I have the vinyl film on three Mercedes and it works really well, It also helps protect from gravel thrown up as you drive.

If you only want to refurbish your door plastic as your seat leather is good then try going to "www.needswings.com" . It is a small supplier of Crossfire parts and and very good support. I believe they have paint available specific for the plastic interior. Send them an email and they will ship to UK. You can also check your local auto parts store for interior paint, but I'm sure you will need to play around and match colors by mixing.

Same thing with the headlights. Use a kit ( many have used the 3m product) and be persistent to get it completely clear. Here in the States many detail shops offer the service. No alternative to replacing a head light other than shell out the money. If the plastic isn't broken, just the rubber seal around the light you should be able to polish the lens back to new unless it has deep gouges. You may be able to find just the rubber seal from a junk yard. The interior of the light housing gets dirty over time. There are several ways to attempt cleaning the interior. I have swished methanol around inside ( I had the headlight removed from the car), but it didn't really make much difference. They were not all that bad anyway and look new from the outside.

Good Luck, and I hope you are right about being a "classic". Hopefully in the not too distant future as they are already 20 years old.