...
Your room should have both WIFI and Ethernet access. Eduroam is the cross-Cambridge WIFI network. Old buildings with stone are not great for WIFI connectivity so there are lots of places around the city and likely within your colleges with no coverage.
Decorating
Historic preservation is an important principle at Cambridge and in the UK in general so the rules about room decoration are fairly strict. You can hang posters etc with blue tac (cheapest place to buy it is Pound Land). Great places to find decorations at low costs are at the charity shops around town or in the Cambridge Market. For example, buy a set of old postcards for 20p each to decorate your walls or print and hang up pictures of family and friends from home.
Security
CCTV (Closed Circuit TV) cameras monitor many parts of College and University buildings and surroundings (including off-College housing). In addition, College porters are monitoring College surroundings most of the time, if not all of the time. Nonetheless, Cambridge University is by no means a closed campus; in fact, it is much less so than MIT, as there is no defined University "campus", with Colleges and departments scattered throughout the city. College grounds, however, are usually fenced off and gated, and those gates are locked at night. Thus, generally speaking, College grounds are more protected than MIT's campus. However, there have been rare incidents of muggings and beatings around Cambridge (just like in Cambridge, MA). The best advice, when you're out at night, is to walk in groups and well-lit areas.
...