I think cup noodles are available on CX long hauls. I've never asked for them as the CX meal is usually filling enough for me (day or night flights to/from SYD), but have read that it's readily available:

http://www.flyertalk.com/forum/catha...y-service.html
http://www.flyertalk.com/forum/catha...ong-hauls.html

Leftover bikkies and peanuts should also be readily available unless it's a really packed flight.

Furthermore you can BYO (food, I mean). You can't bring liquids, but you can bring non-liquid foods. Even your own cup noodles if you're so inclined - CX will provide hot water. They won't heat your BYO food though (hygiene issue, above).

On the feel occasions I feel ravenous I've asked for second serving - read there's something like 105 portions for 100 passengers so there's always a second main to have.

Furthermore there's plenty of ways to kill time on an Aus-HK flight. Movies are great. Or bring a laptop and watch all the back-episodes of whatever you've missed on the ground - every Y seat to/from Aus has AC power.