i really rate irene miguel's teaching, also studio-based - google danzalifestyle or mambolifestyle
'T' gives classes based on eddie torres' shines, but you have to email him to get permission to join, which i heartily dislike the idea of.
for socials - SOS on sundays near russell square tube has a high percentage of on2 dancers and music, and gets you home to bed at a reasonable hour for work on mondays (in case you have a day job)
mambocity, based in ealing, have occasional large events with a high on2 proportion
when i was in london (9 months ago) there werent so many specific socials, but a higher percentage of on2 dancers at the 'dancers' venues....eg, bar salsa specifically on monday and wednesday nights...
good luck with it. and if any instructor tells you on2 is somehow 'better' or 'more with the music' than another beat, please slap em upside the head with a wet kipper from me...
