In very general terms, as a pedestrian in the UK, you have no particular right to step into the road other than at marked crossings, but as soon as you do, you have total right of way, no matter how stupid it was of you to step into the road.
There are various crimes in the vein of 'obstructing a public highway' and so forth, so you aren't completely free to be an asshole, but even if you are, it's still on drivers to avoid hitting you; in my experience, this tends to make drivers more careful and aware of nearby pedestrians, so I'm fully in favour of the status quo.