No brake lights, ESP on and glowplug flashing

[Lance32]

Hi all, anyone on here have experienced this? I've got a 04/05 plate vw 1.9tdi b5.5. I did replace the brake switch but no luck. I haven't checked the the circuit fully but will do at some point this week. What are the key things to test apart from the obvious bulbs, fuse, wiring and switch it self. Any help is much appreciated
If I can also get a wiring diagram that would make it much easier to diagnose.

Many thanks