Hi! I'm also going into year 13 doing my IRPs!
Advice that we've been given from our teacher is that whatever your topic is, you need to make sure you can analyse it, instead of just describing something. Off the top of my head, maybe you could look at how the law has changed over the past few years? You could look at laws and rights for minority communities. Maybe you could look at crimes, a specific criminal.
There's plenty of things to choose from, I'd say first you should brainstorm different aspects of the law you can look at and try and get more specific from there!