Three have a special mention:
http://www.btg-theatre.org/
http://www.kvods.com/
http://www.egoproductions.co.uk/
And the following have been highlighted as sites for further inspiration:
http://www.belmonttheatre.org.uk/
http://www.collegeoperatic.co.uk/
http://www.gino-graphics.com/CATS/
http://www.eldorado-os.supanet.com/
http://www.playhouse.org.uk/
http://www.faringdondramatic.org.uk/
http://www.kingslangleyplayers.fsnet.co.uk/
http://www.masquerade.org.uk/
http://www.oxfordoperatic.co.uk/
http://www.shinfieldplayers.co.uk/
http://www.sideshow-theatre.co.uk/
http://www.southsideplayers.org.uk/
http://www.twickenhamoperatics.com/
http://www.woads.co.uk/
http://www.wos-productions.org.uk/
http://www.wyspas.info/
For everyone not in the above list (albeit possibly not in the London region), the above is something to aspire to ... and for those in the London region not on the list (like me), better luck next time
Rgds
Kenny