Project, they all are...

[Felix2566]

Have done a lot of miles in the car since the Xmas holidays, has been running really well.
Then the other day suddenly had no brakes and rough idle, suspected that there must be a vac leak. It seemed to sort itself out in a few mins.

Then yesterday the brakes went again, no assistance and rough idle. Took the car back to my workshop very carefully as the vac assist never came back. Popped the bonnet and could hear a loud hissing noise, I'm suspecting that the vac jet pump has broken.

Luckily I had preemptively bought one, will have to look at what else I'll need to change while I'm in there.

Can the secondary water pump be tested through Vag Com before I take it all apart?

[Shoppinit]

Check the vac connections to the master cylinder, too. Or it could be the master cylinder failing.

You should be able to hear your after run pump running when you turn the engine off when it's up to temperature. It's pretty quiet so you have to listen carefully.

[Felix2566]

The hissing noise did seem to be coming from the middle area of the engine.

But yes will check other areas too, could take the airbox off, keep the mafs plugged in and have a listen then