You'll need to get a diagnostic done of all control modules and systems to pin point what's gone wrong here.
vagcome should pick it up dash light wouldn't necessarily show up a fault but control modules would
Certainly sounds like the brake light switch..
There were a lot of revisions to equipment in the mk5 Golfs from the early ones to the laters ones so it wouldn't surprise me that this is correct.
And thank you for the info, always good to add knowledge to the bank. Go enjoy her now mate!