Solution: I searched the forums and came across this very thorough explanation by Martin 1810.
http://sites.google.com/site/1810martin ... r-resistor
Basically, the Thermal Fuse is almost certainly the culprit. Ordering 3 new Thermal Fuses (get 2 for backup) costs £2.50 from somewhere like Maplins or you can splash out £35 for a new Heater Pack from VW!
Tools/parts
~15W Solder iron/solder
Thermal Fuse such as this from Maplins:
http://www.maplin.co.uk/thermal-fuses-470
I got the higher rating one as the lower rating one kept getting killed by my 70W soldering iron!
Optional: Multimater to check for continuity
Step 1
Access underneath, behind the glove box remove the foam insert by unscrewing two small plastic screws
Step 2
Just to the left of centre, you can feel the Heater Pack. Unclip the black connector with attached wires.
Step 3
Slide the Resistor Pack out and take it indoors.
Step 4
The old and new Thermal Fuses look like this:
Snip off the old wire
Step 5
The pins on either side are not easy to solder to so you may try to carefully 'twist' both wires from the new fuse around each pin for a better grip and then solder. Once properly soldered to, then snip off the excess wire.
Check continuity with the Multimeter to ensure you have not killed the resistor (like I did)
Re-install and voila, your Heater Blower should be working again.
many thanks to Martin 1810 for this but I thought I would put it out there for others as this is a reasonably common fault.