Maths is required for PPE at some unis - e.g. Durham, Liverpool, LSE, UCL, and strongly recommended at York.
Southampton ask for grade B at AS maths, and list their preferred subjects as -
Philosophy, History, English, Religious Studies, Classical Civilisation, Sociology, Government and Politics.
Manchester has a list of subjects that they would like to see at least one of - including Economics, Gov and Politics and also Geography, English Literature and Maths, plus quite a lot more. You could have a look at their list and see if anything else interests you, and fits into the timetable.
Law courses tend to want you to have essay based subjects.
So there are quite a lot of possibilities - Maths would give you more choices of Universities for PPE, but there are others where no particular subjects are required.
Law tends to ask for essay based subjects, lots of those suitable for PPE would also be ok for Law