I decided to opt for S/U option for both my GEM and breadth module.
GEM: US From Settlements to Superpower - No hesitation to opt for S/U.
Breadth: Principles of Economics - Initially intended to work hard and score but then realised this module isn't easy and plus there are many JC students who took Econs before during A Levels seems to know inside out even without listening to lectures, I think I better opt for S/U.

Hope to concentrate on my CS modules and try to maintain at least a B+ for all my modules (excl HCI since I got a B- for that).