Changed the belt and tensioner this afternoon.
I took the wheel arch liner off, but it was a waste of time and didn’t help with access, so used the camping levellers to get a bit of height and removed the under tray and did it mostly from underneath.
I spent a fair bit of time trying to get the tension off the tensioner to put an Allen key in the holes to lock it, but never managed it, so just lowered the tension and slipped the belt off.
It was fairly easy to get the old tensioner off and the new one on, but not quite sure I managed the 50NM + 90deg on the spline bolt, more like 50+60deg, but it felt pretty tight.
The old belt looked fine and the old tensioner had good spring tension and the bearings were fine. The spring on the old one did feel a bit sticky as though it was getting a bit gummed up and not moving freely. I also noted the belt was overhanging the roller by about 2mm on the old one but not on the new one, so I think the roller had moved over slightly.
Anyhow nice to have a quiet van and saved myself £200 vs letting VW do it.