in london, people dress comfy but still a bit dressed up
skinny jeans with boots
spring scarves
it's been quite nice the last few days, but bring an umbrella lol
DEFINITELY do not go to benefit haha, the blushes here cost £22.50 (thats $45 USD)
Keep in mind that most things are quite a bit more expensive in the UK, so stick to buying things you don't get in america
the well-dressed (IMO) people in london tend to dress like celebrities such as kate moss, mischa barton, sienna miller etc. (quite indie), with good accessories.
check out topshop - great london fashion with some really cute unknown designers
there are some cute drugstore brands here that you could try out, have a look at GOSH and Barry M (they have an amazing heatherette dupe lol)
Superdrug carries these brands, there's one on oxford street.
make sure you go to selfridges - not to be missed lol!
checkout harrods too, very expensive things but it's a really nice shop
look down little side roads and stuff, I've found some really great boutiques on little cobbled roads by just exploring
I love London, hope you enjoy yourself