A law degree gives you a thorough understanding of legal theory and how to apply this to real-life circumstances. There are a variety of subjects within a law degree such as Criminal Law, Public Law, Roman Law, International Law and Corporate Law to name a few.
People to talk to in school: Ms Khanom (Law teacher)
According to UCAS, the average offer for a Law course at UK universities is ABB - HOWEVER - this will differ depending on the university you apply to.
UCAS: https://www.ucas.com/explore/subjects/law
USEFUL SUBJECTS TO HAVE STUDIED: English/History/Philosophy/Maths
University Subject Guide: https://www.thecompleteuniversityguide.co.uk/subject-guide/law
Careers: https://www.ucas.com/explore/subjects/law#careers-where-it-can-take-you