She appeared in Stephen Poliakoff's BBC TV drama, The Tribe, with, among others, Anna Friel and Joely Richardson (a production largely overshadowed by press interest in Friel's full-frontal nudity).
In 1998 she played alongside Alan Davies in "Black Canary", an episode of the BBC TV mystery series, Jonathan Creek, and as Davies' wife in a pilot episode of the BBC comedy, A Many Splintered Thing (of which a series was made in 2000, by which time Isitt had joined the cast of Coupling)
Isitt had a minor part in the film of The Saint (1997), which starred Val Kilmer (as Simon Templar) and Elisabeth Shue.
It was in an episode of the second series of Is It Legal? that Isitt had her first and brief televisual encounter with Ben Miles, to whose character, Patrick Maitland, Sally became closley attached in Coupling. Sally's interest in Patrick has been cited as that of a "size queen".
Kate: I suppose when the series began, Sally was mainly there as Susan's paranoid and needy best friend. She was belligerently single, twisted and desperate. But now all of the relationships have blossomed, and we are seeing more of her independent life. This new romance with Patrick is a big thing to Sally, and it's mutated into something much more for both of them. Now she is living a dream. Patrick really turns her on! He has disgusting self-confidence and is not called tripod man for nothing. He has no morals and very little brain! It's inspired writing, and Steven has written a lovely part for me! Sally and I are very different, but I love working on her vulnerability - on the surface she's cruel, but that's more fun to play than niceness!