Looking at the map in the UK, the vast majority of England is coded yellow or worse (5.6 - 6.0 - suburban sky). In some places you can can get green coded (6.1 - 6.5 - suburban / rural transition), and there's only four areas coded blue (6.6 - 7.0, rural), which are along the border with Scotland, a chunk of Cornwall, a very small bit of the North Norfolk coast at Wells-next-the-sea, and a bit at the border with Wales. Wales in general fares better with some proper dark places through the central and western of the country, as does Scotland in the highlands and along the border with England. Northern Ireland has a few spots of 'blue' in the north and southwest of the country.
Anyway, for me a it's a little disappointing - It'd be many hours drive to get to anywhere rated 'blue' or darker, and over an hour to get to the only place in the whole of the southeast rated 'green'.