Picked up the mirror today, it is actually the entire unit, not the glass only which Camberley Audi seemed to think it would be...
Looked at the clip design on the new unit, figured what I thought would be the way to remove the old one, cracked the hell out of the windscreen due to rushing, due to a million jobs today, due to family coming to stay tomorrow... Made the big ass star-shaped crack even worse putting the old mirror back on the stalk

The only good thing is that the old windscreen was the original and had sooooooooooooooo many microchips in it, but the buggers can't fit it until Saturday.