Elfinsafety i think the crux is "urban areas" I live in Gloucestershire and commute between Cheltenham and Evesham, which means some urban, some minor rural and some major A roads. Most crashes tend to be on back roads where i have misjudged a corner, either ice diesel or gravel. In the urban areas crashes are far more unusual because you anticipate what is going on around you and to be fair force the traffic to do what you want. It is usually obvious when a driver is going to pull out on you, look for there eyes, if you can't see them assume they haven't seen you.
I would also say that London is atypical, the way drivers, cyclists and pedestrians behave is not the same as in most of the UK.
TJ higher speeds do not mean greater risk, there is a risk, but such is life,
If your going to be that concerned about risk i guess you should never go home.
as for pot holes, use your eyes and pay attention, very rarely do they just appear, if your commuting your using the same roads and you will know which sections of road are failing. i can tell you where on my route is going to be an issue come the winter and where to keep away from the kerb as the road edge crumbles. Do not ride in the gutter, do not ride through puddles etc, basic road sense. Like i said earlier pay attention on bus lanes because they are always covered in diesel and after some rain are like skating rinks.
As i said earlier the issue is using your head and controlling your space, it is not about travelling slowly and pissing off drivers causing them to do stupid things, ie increasing risk.