Mathematical biology is usually taken by bio natscis as the pure mathematics covered is applied to biological situations, for example using differential equations to model population dynamics. In addition the course contains a statistics lecture series which is particularly useful for biological options in later years such as the part 1B Ecology course. MB isn’t just for biologists, though, as students wishing to study chemistry in second and third years can still do so with MB. There aren’t really any textbooks I would recommend as the lecture notes are more than adequate. I would advise doing a lot of tripos past paper questions under timed conditions to ensure you can complete the questions in the time given. In addition to the exam, there are practical programming assessments, one of which is Matlab at the beginning of Lent term and the other is R at the beginning of Easter term. You will have weekly practical classes studying these so no previous programming experience is required to do well. For more detailed information on the MB course see http://www.natsci.tripos.cam.ac.uk/subject-information/part1a/qbiol or feel free to contact me (email@example.com).