Pete, you will need a car with one already fitted to get the full kit.
You can use another motor etc....but you will need the sierra bracket that holds the motor in place.
1. plastics,buttons etc..
2. motor.
3. bracket.
4. wiring, this can easily be made.
5. all the screws, bolts etc...
Then the important bit!!
Make sure the motor you get fits the splines in YOUR roof.
I had a late roof motor and it did not fit a 'h' plated car roof as the splines were different, you have to get another motor from a granada or the sunroof from the car which the kit came off.
Any probs give me a p.m.
Dave.