Legal Studies won't help you for Law, but it will let you know if you have any interest in it.
You haven't mentioned anything about your view - only that some teacher said you should do law and that your parents want you to do med.
However the fact that you are posting on this board means you are looking for something above the arbitrary 'do what you want.'
So here are some questions:
1. Obviously, what will you enjoy more?
2. What are you better at? English or science?
3. Do you even want to get in a profession like med or law? both are very difficult professions. Law is very competitive and, correct me if I'm wrong, med students are pretty much guaranteed jobs due to the fact there is a shortage of them, especially in the country.
4. Pay. I don't think either of these jobs pays well for the first couple of years, unlike things like dentistry which have amazing pay. Is this a problem for you?
5. Why have you restricted yourself to these two fields?
6. Are you aware you are not restricted to the subject you do in university? You can do med and change to law if thats what you feel you should do.