I share your pain as I had to do this for my GTI 2 weeks ago. 
My local garage in the Midlands did my cam chain tensioners for £800 (all parts and labour) so £1200 for the same job is rather steep in my opinion. I would try other specialists to see how much they can get this done for you and possibly try price matching with your local one to see if they're willing to budge?
Thanks Patchy. Will definitely try and get it cheaper knowing that now mate. My normal mech should do the work too tbh, but he's not having the best of times were he's working, plus the specialist should give me a warranty which would be nice since he's messing with timing and cams.
Do you need a new adjuster? Because they are not cheap 350-400 IIRC
Sorry to give such a sh*t answer rich, but I believe so.
I told the specialist my car sounds like a diesel, how much for new chain and tensioner. He priced it up and told me £650. And after chatting for a while, he said the tensioner would also likely need changing if we're doing it because of a noisy engine.
Tbh rich, i don't know anyone that will be able to check for me. All the "experts" keep telling me "it's a chain. There lifetime. It dont need doing, time waster" etc. So they don't even bother looking into whether the tensioner needs doing, which we have seen on here are made of playdoe.
For ref. These guys wanted £180 for dsg oil n filter change. I thought they were pretty close considering its london.
