Hi Tony,
The key to Digital radio (and TV and Satellite) is excellent signal strength; otherwise the conversion of all those 0's and 1's into the Today Programme will be full of errors, and you won't be able to hear anything.
We often listen to the BBC on MW, or the World Service on SW all the way down France, but as you head South you notice that the background noise increases until the MW signal is inaudible.
And because digital either gives you "perfect" reception or nothing, the digital signal will cut off well before this point.
A good DAB radio - like the Roberts "CRD 39" which also has an input for your Sony Walkman or iPOD, and works great in the UK.
Oh, by the way, Roberts radios are made by Sangean in China - so if you can find the Sangean equivalent you can save a few pounds.
Robert