I don't think it is possible to save it to the PC, due to copyright issues etc. If you look at the BBC's FAQs with regard to listening again, they mention it it's not possible to forward recent shows on more than five minutes, due to copyright, so I suspect the same applies here. I'd definitely download the show if I could. If anyone knows anything different, please say so!
I suspect we need to do the old fashioned thing; read the Radio Times as soon as it comes out, then set a cassette tape to record the show from the radio on the given day. I used to do that as part of my job about ten years ago, it seems rather archaic now!
treaclechops x