To do law you would need an essay based subject, ie English Lit would cover you. As a facilitating subject it means if you had a change of mind and wished to do English you still could as it is a higher level entry requirement
For social sciences you don't need psychology (I take it though and it is very interesting so I would sill take it even though it isn't explicitly an entry requirement as some colleges don't offer it)
Biology - very good, keeps options up for sciences esp with psychology as well
ART - I presume an entry requirement for art degrees BUT if you aren't sure I just want to warn and say it is a massive workload, + I feel you'd be safer with three subjects that would keep options open for you. But if you like art by all means take it - I love GCSE!
Hope this helps