Your in luck Mike. The most fun you can have with your clothes on, and all on the same weekend. September 26/27/28.
The HiFi Show and AV Expo 2oo3 at Heathrow is organized in part by Hi Fi News and Record Review. You can get all the details
HEREThe other show(s) is/are organized by What Hi Fi magazine. It will consist of Stuff Live! at the Olympia London, which will be a mixed nuts of electronic gear. Close by at the Hilton Hotel, they will be running their own version of the Heathrow show (for Anaraks, et al). You can get all that information
HEREThe various exhibitors are all betting on one organizer or the other to survive this nonsense to fight another day, so, all your favorites will be spread out over half of London. Better plan ahead!