Complex sentence: The library is open to the public, but has very restricted opening times (typically 2.30--4.30pm during the quietest months of the academic year), but it is best to contact the college for current times.
Split into simpler sentences: The library is open to the public, but has very restricted opening times (typically 2.30--4.30pm during the quietest months of the academic year). It is best to contact the college for current times.