I can't run in to work(lack or showers) but I run home once or twice a week. Main problem is getting all the clothes home again. Especially in the winter when Sammy coats slowly end up in my office!
I run accross parts of central london but bikes and pedestrians not actually much of a problem if you plan your route right.
Went to gym yesterday, so got to use their digital scales. 0.8kg down from three weeks ago. If I can keep this up then I would reach target weight in 12 weeks time. See how it goes!