Generally universities aren't too fussed about your A level subjects when you go into a Law degree because it is seen as such a broad subject anyway. Most places I went even said that a Law A level won't help you at degree level for more than a term (and from my friends experience I know this is true.) If you have any universities in mind, just check out their entrance criteria, or have a skim through the UCAS website.
I have just graduated with a Law degree and I'd recommend you do what you enjoy most because this is what you'll do better in, in terms of marks, and generally enjoying your A level experience.
I did Business Studies, Psychology, English Literature, General Studies and Music (nb. some universities don't accept general studies, so always check that out). My best friend from uni (another Law graduate) did sciences, art, maths etc.
At the end of your degree employers will look at your academic record, but also to see what your interests are.
For example, Psychology and Sociology are really good subjects if your interests lie in family and criminal law, because you will do modules about such matters in each of these subjects which will show you have a wider understanding and interest in that area.
Basically, my advice is to do what you enjoy most, because this will be reflected in your work and at the end of the day, most employers look at your academic record before anything else and in interview situations its always really good if you are passionate about what you've done rather than only doing it because you felt it was necessary,
Hope this is of some help!