Hi guys,
Thanks for the advice.
With time running out on me and the weather not the sort you want to lay under a car in I contacted a local garage who is a VW specialist.
The car went in this morning, new valve fitted and all is now fine, around 3 hours work.
Costs however.... New valve £277, labour...............£180, bargain really.
Brought the old valve home to strip down and take a look at, will take photos of the valve and post on here.