Cycling in London looks a lot scarier than it is - but of course it depends how comfortable you are on a bike, mixing it up with cars, in the first place. Just be confident (easy to say, I know), and be very aware of everything that's going on around you. Like anything, becomes second nature after awhile. And remember that you have just as much right to be on the roads as motorists. Scoobie mentioned Critical Mass: one of their mottos is 'We are the traffic'.
As for commuting, it depends on the commute in question, but in general it can be a great way of getting to work. You arrive feeling very refreshed and energised.
I've cycled all over the UK, including the end-to-end, which is Land's End in Cornwall to John O'Groats in Scotland. I think it's the best way to see this country, and as a mode of transportation it's actually quite safe - at least that's what the stats say. It certainly is in my experience. And it's extremely good exercise.
Any other questions about life on two wheels, please ask.
