BBC chart for DAB coverage is pretty poor for anyone living along the coastline of the UK... and coastline means inwards of 30 miles or more... the commercial coverage map seems very good though, I'm not sure if it really is that good though.
Apprently, the DAB frequencies 'could' interfere with France, boo hoo, so the BBC have had to have been very careful about DAB not crossing the channel, sadly they seemed to go overboard and played it safe by avoiding the coast at all. It's probably going to take them time to go around and fill in the gaps, for example Brighton now has DAB, but no one outside of Brighton can easily receive the signal (and many inside Brighton can't either!)
< BBC Coverage Map Here>
Interesting that the commercial Digital 1 multiplex appears to give much better coverage for us Southerners.... compared to the BBC's .