In reply to ElBarto:
Try bremex,
I oringally joioned it about 25 years ago,
back then we learned about navigation, mountaineering, climbing and generally how to move and cope with less experience people in the hills
http://www.bremex.org.uk/about/
I came back to Bremex after a 20 year break, after being invited to the Bremex 50th anniversary celebration.
http://www.mountain-training.org/news/-bremex-trust
Memebrs are no longer based exclusively in London, since returning I have been walking and climbing with members as far apart as Brighton, Bristol, Nottingham, Lancaster and me Manchester(ish).
Good luck with whichever course you may choose
Richard