Being an avid fencer I'll do my bit and plug the UCL Club:
First and foremost - they have an excellent coach. He is a friend of mine (a coach at my London club actually) and he's a really nice, tall, Russian guy.
Fencing is great, not only for the high level of fitness attained, but also for its social attributes. If you become a reasonable fencer and start doing competitions you'll find yourself submerged in a 'small' (~800) circle of people, all of whom are great people and from varied backgrounds.
It's also a sport for all abilities, ambitions and ages (5 years old to ~80 I think!). It's also a great outlet for violence, re: sabre!