There is a student Mathematics society, called the ADM Society, which organizes events in the Department, publishes a newsletter, etc.
The UCL Undergraduate Maths Colloquium will meet weekly during term (Mondays, 5pm, Room 505) to discuss and share interesting mathematical topics outside of (or complimentary to) our normal lecture courses. Each week an undergraduate gives a talk on a mathematical subject or problem, e.g. padic analysis, analytic number theory, general topology. We occasionally spend time working through problems from said talk.
The Colloquium is open to all and the talks should be accessible to anyone with a first years' undergraduate background in mathematics and/or a willingness to learn. We hope to encourage all current undergrads (regardless of their mathematical background) to attend and/or give talks.
We now additionally organise weekly Study Groups on a variety of topics, including General Topology, Representation Theory, Modular Forms and Network Theory.