The University of Cambridge publishes the dates for both Term and Full Term well in advance, and students should make sure that they check these when making any travel arrangements.
Each academic year contains three Terms, and part of each term is designated Full Term. Full Term refers to the period of just over eight weeks during which all lectures and teaching will take place. It is an intensive educational period, during which all undergraduates are expected to be in residence. If an undergraduate is not in residence for the whole of Full Term (if, for example, they spend a weekend away), then they must make up the difference with nights spent in residence in the main term, totalling:
Michaelmas Term: 59 nights
Lent Term: 59 nights
Easter Term: 52 nights
There are also regulations and expectations regarding graduates' residence and study in Cambridge, which can be found here Graduate Terms of Study.