Congratulations on the new job. I hope you enjoy London. Best tip is to get on the tour bus and check out the sights - then go back to the ones that attract you. Second best tip is avoid the Underground like the plague. Dirty, over-crowded and unreliable. Buses and walking are better if you can manage it.
Aperture is a great shop - Richard and Patrick have done me some good deals in the past. It's not cheap gear but they are very competitive for good quality equipment.
Nigel, thanks for the heads up on the appeal. Patrick's wife is Japanese and took my wife's and my photo when we went in there the other weekend to pick up a lens. I have a couple of bits I'll take over there for them to sell.
Another good place to visit is Camera City, just round the corner from Aperture. York Cameras is a good shop but I always find them quite pricey for gear that sells for a fair bit less elsewhere.