Thought i would update this... Got dashboard out (pretty easy actually!) and could finally strip the soundproofing material out, to see where this leak was coming in. Turns out there is a hole in the same spot as the bonnet release cable, presumably for LHD cars. VW put a metal bit in there and pressed into place, and sealed it. Seems like after 24 years the seal was slightly weak, and let the occasional drip in. Sealed from the bonnet side, and all good! Never really noticed the metal plug there with all the waxoyl on top of it, and it looks like metal so assumed it was just a moulding shape or something, not a plug!
The hardest part was getting the dash back in with the wires in the right place! The switches have all gone back in the wrong order, i think i twisted the loom slightly, so the longer wires go through a different hole! The best bit is having it all back together! Started this around February when i removed the carpet, seats (except drivers) and most of the dash, and i've been driving it like that for months!
Hope it helps with future leak proofing?!
Quick pic, but cant see the metal plug
