Hi Stewart, and :welcome2: to LZ.
Everything can/must be done with the window up.
There are 4 screws along the bottom of the door-card only.
Then you pull the card away at the bottom to release the card from the plastic clips. Then up out of the top clips.
You don't need to take off all of the inner plastic film - just the top RH corner.
The nuts are accessed through holes in the door panel, working from the inside, I used a 1/4" drive socket to reach them, as I did not have a double-jointed dwarf available. It would be pretty tricky if you only have a set of open-ended spanners.
Be careful you don't drop the nuts and/or the socket into the depths of the door - they are difficult to retrieve.
Most handles fail due to rusting of the bolts in the handle itself. Rub some grease over and around the holes on the outside of the door where the bolts pass through.
Hope this helps you.
Cheers, Singvogel.