Sociology is perfectly acceptable. Ignore "Anonymous1502", or rather, read through their other posts and make a judgment on how much you value such a year 12 student's opinion - particularly given they're not even applying to the same subject, and their approach to apply to their own subject is questionable at best.
Your subject choices are fine, provided you're interested in them and are confident you can get As in them. You do not need to change the subjects unless you aren't interested in them. Science subjects are no better preparation for Law than Sociology or RS and worse in the sense you don't have as much analytical essay writing preparation for when you actually get on the course.
While STEM subjects are reputable, Sociology and RS are, despite claims to the contrary, perfectly acceptable by almost every major UK university. The only one I know off the top of my head that would have any qualms is LSE, who are quite choosy about subjects. Even most colleges at Oxbridge will find that combination acceptable.