If you can manage it, do all 4. A lot of people applying to Oxford will be getting AAA at A level. Otherwise, Economics is more likely to be of assistance than Mathematics - complicated calculations aren't really required to read law.It's also important to start reading about the law now - read the Times law section. Read law blogs. If you do maths, read around and find out which law lord of the 20th century converted to law from mathematics...
