I know it's further east than you wanted but when my A4 was younger and I could justify the cost I used these guys a fair bit, Euro Performance in Pontyclun.
http://www.euro-performance.co.uk
The place was always full of VW's, Audis and BMWs and they seemed to know their stuff.
They only used Genuine parts from TPS and I never had any issues with any of the work they did.
I haven't used them for about 4 years as the last time I needed a big job doing (a clutch) their hourly rate (IIRC it was about £60 ph then ) made it more cost effective to get the OEM parts myself and pay local garage to fit them.