I don't do either Psychology or Law, but I'd recommend UNSW or Macquarie. I can't recommend Usyd cause I don't know anyone who has studied it there.
Macquarie you can expect a competitive, by-the-books environment. Macquarie has a reputation in the psychology community that it certainly wants to keep. I've heard frustrating things about the 200 level Psych subjects, but beyond that- a psychology degree at Macquarie is seen as hands on, gives opportunities to combine it with linguistics and criminology, and overall apt preparation for honours.
UNSW is also terrific. Alot goes on there, it has a wide community of students and alumni, opportunities for experiments, etc.
Really- you may want to use UNSW's trimester calendar as a tie-breaker. Both are fantastic. Note that psychology is pretty full on and is rigorous (its not uncommon for Psych students to take extra subjects in statistics, to gain confidence in the 'hard science' part of psych.)
What are your career goals? Why law as well? Do you see the two fields meshing well? If you are interested in say, forensics maybe a secondary science major would be better than law. Biology is a great starting point for Psychology, but I'm curious to where your passion and motives lie for Law. It's a time consuming degree and costs alot. You need to justify that down the road.