I have visited the UK on three occasions, and have driven around 20,000 km or 12,000 miles on those trips, mostly in motor homes. I have to say that I was impressed with the courtesy of drivers during that time, whether on motorways, A and B roads, or country lanes. My last trip there was in 2008, so maybe the standard has deteriorated. We have some very ordinary drivers here too, and the standard is definitely deteriorating.
Peter.