Police don't have to knock, CNN article

[DanaC]

I'm going to the UK for a few days in July, and I'll be completely disarmed the entire time

Unless you look like an Arab or a Pakistani you'll be fine. Very few guns over here compared to over there and very few gun deaths.

If we look at America's record over the years, we could probably find many more incidents of people being shot by police unnecessarily than over here. You'll be fine:P