BBC uses dynamic URLs for flash streams, so I don't think you can use them the same way as Windows Media or Real Media streams.

If you still want to find RTMP URL of BBC radio station, you can use CooJah.

Windows Media streams are still available. I suggest you to use them. BBC will probably offer some alternative to RTMP streams in the nearest future, because many people won't be able to listen to RTMP streams.

Related:
Cannot detect url in BBC iPlayer