I agree with John here about Dab - the bitrate is so low on most stations (normally 128k MP2 - yes, MP2 not MP3, so inferior coding, and low bitrates) that I wouldn't spend too much on it.
However, Freeview is better, and Sky is better still. Most stations transmit using 192-256k Mpeg2 which is a better codec than MP2/3. I'm actually listening to Classic FM through sky at the moment, and it sounds lovely...
If you don't have sky, the boxes/dishes go for next to nothing on ebay, and fitting one is about a 1/2hr job (excluding running the cable from the dish to the box). You won't need to subscribe to sky to pick up the radio channels - they are FTA (free to air).