There's a lot on during Welcome. The Welcome Tent runs drop-in activity all week, the Students' Union holds society fairs, LIFE in London takes groups out into the city, and teams across the School - Learning Lab, the Library, Careers, the Volunteer Centre and others - run their own sessions.
This page shows everything that's open to all students. Your department will send you its own schedule separately, including enrolment, course selection, presidential address, and your programme introductions.
Events are grouped by theme, so you can start from what you want out of your time here rather than from which team happens to run it. Plenty are drop-in, so you can just turn up, but some need booking in advance - check the listing before you set off!