I'm curious whether you know of any undergraduate degrees that are exclusive to the study of natural law. If there are none that you know of, do you know of any program that has natural law as its main emphasis?
No, I don’t think there are any such programs, but don’t be discouraged; there shouldn’t be. The best way to prepare for the study of natural law is to get a broad, classical liberal arts education which is heavy in ethical and political philosophy.
Of course you will want teachers who are well-informed about the classical natural law tradition and sympathetic to it. It would be wonderful if they taught other subjects, such as history and psychology, from the perspective of natural law. You should supplement your classroom studies with independent reading about natural law, and if you tell me what you’ve read already, I can suggest other things to read. But I don’t think it would be good to try to turn natural law into the whole content of your major, even if there were such a program.