A404 and the A404(M), between Maidenhead and High Wycombe. Quite fast, corners, hills and roundabouts, where you change down listening to the nice sound if the ol' engine revving high :)

Milton Keynes A43 The stretch from Duddington to Corby was pretty good with nice fast bends and hills etc.

A52 Nottingham -> Boston : good fun, some nice wide open bends with miles of visibility, raised from the surround flooding plains.

http://www.speedlimit.org.uk/drivingroads.html