Depends on how good the DAB reception is where you live really. The Denon DM38 I had and the 603 I have now have both been connected to the TV aerial and my reception is great, never had a problem. If you have a FM aerial then that would probably be fine as well. FM band is 88 - 108Mhz, UHF TV band 470 - 854 Mhz, while the DAB broadcasts are kind of in between the two at 217 - 230Mhz. Its worth trying, as putting up a dedicated DAB aerial may not give you any better reception than you currently get.
The DAB connection on the back of the 603 is 'F' type connector. A visit to somewhere like Maplins will sort that ought. Some are just screw-on to end of the cable type so no special tools required to attach it. If you ask them nicely I suppose they may even make up an aerial lead for you with the right connectors at each end. Don't expect it would be free though.
Rich