Checked the hoses to the heater core Bagel and they appear to be fine (thanks for your help with this, most appreciated)(see previous posting). Cant smell anything from inside the car (normally a sign of leaking heater matrix) so hopefully the matrix isnt leaking. I'm sort of thinking it might be something to do with the pre-heater (maybe). The fluid must be going somewhere, and seeing as its not leaking externally it surely can only be leaking internally. I do know one thing, and thats that i'm pretty peeved at a VW of this age having these sorts of problems.
Any ideas are most welcome (very reluctant to take it back to VW when their only method of diagnosis is to replace all relevant parts until they cure the problem)
A couple of days after writing this however i have again found fluid patches on my drive (approx. 10"-12" in diameter, and definitely coolant as the tarmac has turned black, like its been melted slightly)....it looks like the leak is back to full force again.....think i might have to concede on this one, possibly go back to the dealers.