I've fitted loads of the Vent Axia Luminair fan\light combos. I've taken on board the less area for extraction, although they have 2 large open sides rather than a grille on the front and a lot of vent terminals have some sort of restriction so I'm not convinced that's a completely valid argument for condemning them. However, as per the original question, the Luminairs are individually fed from a single SELV transformer\controller so the light can be wired into the lighting circuit in the room and the fan kept separate if needs be.
You can also get something similar to the Manrose kit mentioned above bit in separate parts. I've fitted a couple of vents with lights and then added my own inline fan and these also can be wired independently.
