Well, helpful bunch on there ... over 100 views and not one reply in three days!
So I emailed Rosstech asking about the CANbus on a 2003 Golf as their web pages state my car wasn't fitted with a CANbus, but VDCS was scanning it and returning results.
Very helpful answer ... our Golf apparently was an odd-ball which had a "virtual" CANbus built into the "Instruments". Trust me to buy something screwy!
He was kind enough to suggest that my problem may lie in a thing called a Convenience Module which I am able to locate. So more fun and games replacing and, I think re programming this Convenience Module!
And people wonder why I stick with an old Discovery.