BLR 2.0 FSI Skoda Octavia: Replace timing chain of camshaft

Hello, I just got a 2005 Octavia in. The engine is making an extremely loud rattling noise, like a timing chain that's about to break.
The relevant literature is not available online. I have now removed the valve cover, the camshaft adjuster cover, and the high-pressure pump (the tappet on that is intact). Now, the chain tensioner can be easily pressed down.
I ordered the tensioner and chain from VW as a set.

But! How do I remove the chain?

Does the front camshaft that actuates the fuel pump need to be removed? There's a long slit in it!

Okay, there's really no literature about this. I asked a mechanic at Bosch Service, and luckily, he was able to show me a guide. It's quite simple: 1. Turn the engine to its top dead center (TDC) position. 2. The camshafts have recesses that allow you to loosen the cylinder head bolts. You can only loosen the head bolts when they are in the TDC position. These recesses must be perfectly parallel to each other. There's also a special tool for this, which looks something like this: |-|. But anyone who can look straight ahead can manage it.