Networking is you making connections with new people and their own connections, which can open up opportunities for you. Cambridge is a small place, and you may soon find that your specific field of research is also a small place too. With a few constructive conversations here and there, and some following up, you can usually find other people who you can help, or can help you with whatever your interests are. Don't underestimate the power of networking! More and more research is interdisciplinary these days, and many of the projects that get funded are interdisciplinary.
Cambridge is full of opportunities to network. Colleges are ready made networking scenes, but you should also look out for Department events, as well as the breaks in seminars, conferences, and symposia; these can often be the most productive times for you!