Law is an extreme amount of work, unless you're interested in learning loads of acts and facts, are interested in the content and have a reaaaally good memory then by all means go for it.
I believe Law is also not favoured by universities as an A Level.
Sociology is extremely interesting with minimal work required, it is essay based which should be suitable for an English student.
This is my opinion and I wish you much luck. May I also ask what your other 3 A Levels are?