Okay, I made sure illuminate by default was ticked, no dice.

I've made some progress though! I tried throwing a primitive in to the scene to see whether or not it would render, and lo and behold it did! I still can't see the fluid though, which is a shame.

The primitive (a sphere) that I chucked in shows up in the render as a solid white circle, which seems to suggest that it is indeed a problem with the lighting, although I still haven't figured out what.

EDIT: It might be because in the original file (the one that I modified to make this one) the fluid is remapped around the surface of a sphere. I've since deleted the sphere, but maybe it's still trying to remap the fluid to an object that doesn't exist.

EDIT: Damnit, I gave up trying to fix the problem and decided to recreate everything from scratch, which was working perfectly (including having the fluid container appear in render view) until just before I decided to try and render everything out. Now it's black again. Infuriating!