You can find hearts, livers, kidneys and stomachs, but except for chicken livers, pretty much only in halal (i.e. middle easterner) butchers, as far as I can tell.
Edit: Most English also tend to find blood saussages disturbing. There's black pudding, a blood sausage they make oop north, in Yorkshire, but people under the north-south divide won't go near it with a ten-foot pole.
And you should just see the expressions of disgust towards haggis (a Scottish dish made with innards and quaker oats).