Well on the digital radio channel, BBC 7 are broadcasting the Eighth Doctor audio story, Shada
Written by Douglas Adams, it was originally made during the Tom Baker era, although a technicians strike towards the end of filming meant that the story got shelved and became the only filmed Doctor Who story not to make it to the screen (although a couple of scenes wre used for the twentieth anniversary special, The Five Doctors when Tom Baker refused to appear and the story was later released on video with Tom Baker narrating through the missing links).
That said, a few years ago a company called Big Finish started making new audio adventures of the series and one of those made was Shada.(Although they had to slightly rewrite it, taking into account the scenes used in The Five Doctors and made out that this was Paul McGann's Doctor, fresh from his adventures in San Francisco, meeting up with Romana and K9 before setting off to 1970s Cambridge (where some of the events take place)) The Doctor Who website has been broadcasting it for a while now and you can find it here.
If you want to see a Doctor Who story written by Douglas Adams that involves Cambridge, cups of tea, an in-joke with regards to a Hitchhikers character, K9, a Time Lord's prison planet, a TARDIS (Not the Doctor's) disguised as a... (Now to mention more would be a spoiler)
Then I warmly recommend it.