The year walk-about was completely unplanned and at that stage, she was forced to commit to it. However, Martha does mention her studies in the present tense and does use her basic knowledge a couple times during the season.

But most of all, when the Doctor is trying to get her to join him initially in Smith&Jones, she mentions her studies, and he says 'it's a time machine, if it helps'. So she understands from the get go, that she can recoup whatever linear time she's lost and her career is not in threat of being waylaid.