This chart, kindly provided by NATS, shows the coverage area of the UK by NATS ADS-B ground receivers for ADS-B Out equipped aircraft flying at 3000ft. The chart is correct as at 30th October 2015.

The colours indicate how many ground receiver sites (from one to six) cover the area, according to the legend on the left.

NATS UK ADS-B 3000ft Coverage Area Oct 2015

NATS UK ADS-B Ground Receiver Coverage Area for aircraft at 3000ft (Oct 2015)