Lost in Space (and Time) by pandarus. Doctor Who/Black Books crossover fic.
Status: One-shot. Complete.
I really like the pov in this fic. Having Manny and Fran telling a disbelieving Bernard about their adventure was a stroke of brilliance on the author's part. The dialogue was perfectly in character for Black Books and was pretty fun as well. It's only problem is it's a little too wordy.