Start with the Necrons; they are not picky about food or social interaction. Give them a schedule for the entire day, and they will continuously dig and build, making them the ideal race to focus purely on military operations.

Orks are hella fun. I usually start with a Warboss in Naked Brutality and turn on 'Losing is Fun' mode. Just a warning — even a small patch of orkoid fungi will start pumping out spores like crazy. You’ll end up with a swarm of little ones real fast. Total chaos, but that’s the fun of it.