Mary - if it is on BBC Radio 4, it will be broadcast online - I'll find a link......HERE IT IS....
That will get you to Radio 4's web pages. You can listen online live but you need to have RelPlayer to be able to do so. The programmes are also kept on archive for a week after broadcast, so can be picked up later, but then for some legal reason the archive is removed from public view.
If you want to record such webcasts on a Windoze PC, there is a programme called Total Recorder, which hijacks the signal before it reaches your computer sound card and can record Real Audio. You can find Total Recorder HERE . The "standard Edition" is relatively cheap, and does a good job.
Quack!
Geoff the Duck.