At this time of year there are many unofficial freshers Facebook groups or pages established. Many of these are set up by promoters or companies to gather students' personal details in order to sell them products and events. These aren't associated with either the University or the Students' Union.
The following are official Warwick Facebook pages. Your department may also contact you through an official email to endorse other groups which should be safe to join.
The SU Freshers group below will provide updates, the official Freshers events programme, and it is the best place to meet fellow students.