I did work experience at a Law firm and when I asked about what IB subjects I should take to studay Law at uni, one of the partners of the Law firm told me to do something different. Law firms recieve a lot of similar applications that show no variety; so doing something that makes you stand out is a huge bonus.
You have to take English, Maths and a language anyway so take subjects that you really enjoy and that you think make you stand out.
I've gone one step further and I'm studying Psychology at uni before doing a conversion course into Law. It means I'm studying a subject that I love and that I'm bringing something new to the table when I do apply to Law firms. It helps you to think outside the box when you need to apply your knowledge to real life situations.