I found libraries productive but if you know a lot of people there or your friends are going, chances are you won't end up doing much work unless you are all equally committed to studying. As a uni student who also studied at the public library, once 3pm came, there was always the kids who rocked up with a football, some without even having any books, and all they'd do is sit and talk (and annoy everyone else who was actually trying to study or do work). I bet after HSC results came out they probably wondered how they did so bad given they went to the library every day.
So the two points I'm making here are:
1. Will you be efficient and effective studying there (compared to being at home or elsewhere)?
2. Will you be able to cope with other people being ineffective and distracting?