You should be able to reuse the existing butyl tape (a few times actually) . Just be careful when you remove the polythene sheet. Start from a corner and gently pull the polythene out, making your way around the edge.
Safely store the polythene, making sure it doesn't stick to anything, and make sure the car's interior doesn't come into contact with the bare door as there will be some butyl tape left on the door. They're damn hard to get off stuff like fabric seats.
If I were you, I'd take the car with the moisture barrier and let the garage handle removing it and putting it back. The winder might be accessible just by removing part of the polythene, without taking the entire thing out.