As well as the bedroom there's:
for buying/listening :
http://www.accessallareas.org
http://www.bangingtunes.com

and more good record shops in Soho, Berwick Street and elsewhere

For going out check:
http://www.lost.co.uk
Http://www.retroverts.com
http://www.londontechno.co.uk
http://www.truelove.co.uk

Used to know some good midweek techno nights but unfortunately they don't seem to happen so much these days, maybe George 4th brixton??
I may well be missing something though as dI on't go out in the week these days.
I recommend checking out a retroverts night next time they have one, or try a free party if your into them (Maybe look on squat juice site for details).....depends what sort of techno you like i suppose!
Anyway....enjoy your stay.