According to the 2 New York Times and LA Times reviews of the film, we won't see much of Jennifer Ehle though:
Math professor Allen's recent affair with a lovely colleague (Jennifer Ehle) provides a potential key to the marital problem between Allen and Grace that clearly predated their son's death. But, like much else here, it goes underexplored. (LA Times)
The film squanders valuable time on several undeveloped subplots. One involves Allen's recent affair with a colleague (Jennifer Ehle), who tries to offer solace. (NY Times)
Colin Firth talks about his role as King George VI in The King's speech :
I finally fall on this very funny article, Postsecret and embarassing Pride and Prejudice confessions, in which the author archly asks : what hidden secrets do we have about Pride and Prejudice? I let you look at the post and meditate on that...