I came across this via a meetup group i belong to and thought it looked interesting. You don't need to belong to the meetup group to go and you just pay what you can afford. I would go but it clashes with a poetry reading course i've started going to but i def would if they have it again. It says social anxiety but this would be a good confidence boost for all sorts of people , i think.
Social Anxiety Inside Out '2 Day Relaxive' Tickets, London - Eventbrite
I know they ask for money in advance but i think it can be trusted. Check out The London Shyness group/ Leading Light group on Meetup.com as it's on there too. The guy has been running that for some time and i guess people do do things for altruistic reasons even in these hard, cynical times. I guess you could pay £1 and then the rest when you get there and know it's genuine but as they say they need an average of £20 from each person to make it pay for itself so be reasonable otherwise they won't do it again and won't help other people like us.