The only places I know of are near me in Middlesbrough/Stockton.
Volkswork - VW and Audi Specialists
Ron Turnbull - As above
Falcon Performance - A friend uses these, he swears by them. He's had his S3's in for loads of work...they know their stuff and have VAG-COM. Little on the pricey side but no where near as much as the main stealers. HIGHLY RECCOMENDED!!!
Can't go wrong with Elite Vehicle Services, Glasgow Street, Stockton on Tees. Ex Audi technician, does great work with great prices. For example, he did a full service, changed the Cambelt, Waterpump, tensioner, Hydaulic damper and timing chain adjuster gasket all in for £495, 2 years ago.