Okay, here you go. Several people have asked me about this.
There are several venues that feature free improv/experimental music. I would recommend [u]you go and see a gig first [/u]rather than send links to the promoters concerned. Talk to whoever runs them in person.
In addition to Cafe Oto and the Vortex....
[b][size=4]The Dog House in Kennington - Vimeo have several vids from this venue - so maybe start there. Very Free-improv (two venues)[/size][/b]
[b]Club Integral - several venues, so look them up - avant bands mostly and small ensembles[/b]
[b]Lewisham Arthouse - Charles Hayward, the drummer, runs this. Invite only - so go to a gig first[/b]
[b]The Hundred Years Gallery - Kingsland rd, a small basement space - small ensembles[/b]
[b]Ryans Bar in Stoke Newington - I've seen small avant bands play there in the basement[/b]
[b]The birds Nest in Deptford - loud, rough venue suitable for small bands[/b]
[b]The Montague Arms, New Cross - run by a collective - stage/PA/ bands[/b]
[b]Servant Jazz Quarters - Dalston - cosy basement venue often used by Club integral[/b]
[b]The Mopomoso club - free improv - two different venues[/b]
[b]Boat-Ting - a nice venue on a boat moored on the north bank. Monthly improv gigs[/b]