Hi, I was just watching a video by VAG Technic here:
https://www.youtube.com/c/VAGTechnic
It shows how they open up a V6 engine to change the chains and tensioners. They would probably be good guys to contact as they really seem tto know their stuff and the cost looks reasonable. They are based in Dudley which isnt too far from you. I'd definately go to them if I wasnt out in the West Country.
Best of luck