There is a blues/country/pop jam session at the Spotted Dog, Upton Lane, E7 on Thursday nights. This is a session that has been moving around for a while after being there originally on Friday nights. I've seen about twenty guitars there on one night!I think there may still be something going on at the Theatre Royal, Stratford, E15 on Saturday afternoons and at the Golden Fleece. Capel Road, E7 on Sunday afternoons.
I play at a mainly Irish session at the Old Black Bull, stratford, E15 on Thursdays. It's mainly instrumental but singers are welcome.