The information for NatSci at Lancaster says this:
"In the first year, all students begin with three pathways. You must choose two science pathways, and a third that can either be another science topic or you can select from elsewhere across the University, including a range of humanities and social sciences."
I can't seem to find which other subjects you can take, exactly, as it seems pretty vague. If possible I would like to take linguistics with it, but I don't know if that's possible.