The libraries are especially in during semester exams have been full. Before going there, it would be easy to have a simple app displaying libraries close to one and their occupancy.
Edinburgh University's Libraries use traffic light based system,
with Red light indicating a full library with no free seats
and a Green light indicating plenty of space.
University College London View
University of Passau View
See Articles on Occupancy Monitoring Application for University Library
3. Study Hunt: Library seat availability live monitoring system View