parallel

I wish to build a metal stud wall to partition my loft, there is a loadbearing brick wall I can build upon BUT if built there the ceiling runner ends up centered parallel with the rafters and have nothing to attach to. The best I have come up with is adding some noggins (in red) 600mm apart...

I know this has been posted before, but in some old threads... and some of my questions aren't in there so I'll start a new one rather than try to resurrect them. I'm hoping to make an LED 'Hollywood Style' mirror for the other half. Making the unit itself I am fine with and I know it'll look...