In my experience, there are more people in
HR with psychology degrees than
HR specific degrees. I too am a
HR practitioner with a psychology degree and probably similar to you, after wandering aimlessly through the first 2 years of the degree not really seeing myself going mainstream psychology.
I think one of the best things you can do at this stage while still at uni is to take as many org psych based units as you can, or additionally, take management/
IR/
HR electives from the business school if you're able. If not, not to worry, I didn't think that far ahead.
Second, while still at uni I'd look for some work experience and/or vacation work somewhere in
HR if you can get it. You'll hit the ground running when you graduate.
I really wouldn't worry about doing
HR specific study straight after your degree. It'd be best to get stuck into an entry-role in
HR really and once you get established, perhaps look at going back and doing a Master of
HRM (or even an MBA) while you work.
But it's great to read that you're looking into such a career path... it's exactly what I did and have never looked back.