Hi there!
Universities aren't necessarily looking for a fully-fledged perfect student- what they're looking for is passion and potential. You're clearly passionate about studying law, and it sounds like you're willing to put in the work to make it happen- don't doubt yourself!
If you want to improve your public speaking, see if your school or college has a debate team- they're a great way to practice constructing an argument and delivering it in front of an audience. If your school doesn't- why not see if you can set up one?
If that's not possible, see if you could get involved in a theatre group- often you can just go to theatre workshops near you without having to perform on a stage in front of an audience. I went to a theatre group as a very shy 13 year old and came out a very confident student! Even if theatre's not your thing, it definitely helps with not feeling embarrassed and with public speaking. You can learn how to project your voice, pace your speaking, and feel confident in yourself.
Best of luck in the future!
-Ella
Graduate Advocate