Good comments already mentioned.
My advice would be similar to FFF's, and seeing as you are on a part time basis, I would do the Air Law first, conventionally, and then attack the exams that are most related to theoretical subjects, as oppsed to the ones more relevant to practical flying. After Air Law maybe try Human Factors, and then maybe met.
I can understand your eagerness to get them out of the way so you can enjoy the flying, however I echoe the comments about making sure you learn the topic and not just the answers. Personally I found the whiz wheel very hard to get to grips with on my own, but it was easy as pie when talked through. So on that note it may be worth waiting to do the more practical exams.
Ideally Nav, RT, Air Tech and Flight Planning & Performance are perhaps best left until at least some flying experience and instructor time has been had.
Very best of luck with the PPL!
Regards,
Rusty.