us vs uk, is there a difference?

I've heard that English women are more likely to take the initiative in a social situation, when she sees a man that she is particularly interested in. Where as in America the man is sort of expected to be the one to handle the approach. Naturally i was curious as to the level of truth, if any, in these rumors. I will be travelling to London in July and living there for a few months and would love some input from you boys and girls over the seas. thanks a bunch!