Hi Benny! Being that local no doubt I'll probably see you around!
Yup VW in Little Chalfont is my local. They are part of the Citygate network. I had it in there for a service & MOT earlier this month, simply for convenience. They were good enough service wise. I've not tracked down a reliable local specialist yet, but Amersham is packed full of independent mechanics garages!
The obvious VAG options I can think of are Fontain in Iver or Yaash (Yaashik Motors) Motorsport in Park Royal/Wembley area.
However there is also Phil Crouch Engineering in Amersham opposite the Audi garage.... they are one of the best BMW specialists in the country, but also have experience in VAG cars. I've not yet used them, but will explore them as an option next time I need mechanical work done. My cousin has his E36 M3 and 635csi maintained by them, and swears by them.
http://www.cpcpe.com/