Have not phoned the dealers yet as I've found some tech bulletins on vwvortex about leaks / blocked drains etc. so intend on having a little look myself before trusting anyone else. I'll use the diagrams and instructions listed in the bulletin and try not to break anything / make anything worse!
However, not sure what to think now about the Krytox. Before it only leaked in the back left of the boot. This morning there was quite a bit of water (after the snow) in the back corners of both sides of the boot!!!! That's right, the Krytox application seems to have made a new leak (if that's possible) or more likely I haven't applied it properly! I suppose it didn't help that I used it in freezing temperatures (over the following days quite a large amount of it appears to be running down the windows). So I can assume that very little was actually absorbed into the seals themselves.
Anyway, I have the luxury of a week off week in a weeks time (an advantage of working in a school!) so I will have a proper look during the day then, and try to see where the water is getting in!
Thanks for all the help from those who replied on the forum / pm and I will post again as soon as I have any interesting / relevant updates, be they self solved, dealer solved or more likely 'oh well, it'll stop raining and be summer soon'