As far as I know the clubs don't offer any lessons or anything similar anymore - A couple of years ago The Vic used to have a beginner tournament on a Sunday where they had an hour of lessons prior to it but that doesn't happen anymore and to be honest had zero value with the speed of the blinds.
What I would advice you look at is either a pub game where it is a lot more social and more focused on fun OR a beginner tournament such as the Tuesday night game at The Gutshot or the Friday night game at Loose Cannons. Both games are made for beginners and all the players are extremely forgiving.
Also - Just to add, not sure if you read this
http://www.londonpokerdirectory.com/index.php/London-Poker-News/Playing-live-poker-in-London-for-the-first-Time.html but I think it sums up some of the worries people have about playing live and I have to say you have nothing to worry about, the London poker community is very friendly and always welcomes new people.
Oh and maybe try playing poker online a bit so your friend can get used to how the game is played and boost their confidence with the basic rules.