I finally had another go at this image tonight, and I'm quite pleased with my progress so far... I am extra pleased with what turning off "Haze" did. Turning off haze made my image go so much darker! But I've gotten lost and need some advice.

Orbital's method of using the "volumetric spheres" instead of the Skylab, which I agree with since the clouds are rather flat and don't behave well in Skylab - or they don't behave well for a newbie like me - how exactly do I set up a "volumetric sphere"?

I can guess it's one of the tools on the top bar, but which one? Create Sphere? Create radial light? Create dome light?

If it is the "Create Sphere" option, are the clouds one of the texture options... like the glass? I'll continue to have a play around - I'm about to try the spotlight that orbital suggested but thought I'd ask about the sphere thing and to show you what I've managed so far.