PIR Insulation between rafters - Cold Roof

[SS-ProjectBuild]

Hi Guys,

I am about to put in my insulation between the rafters after my electrics first fix,

The question being do I put the insulation in so they are flush to the bottom of the rafters or can I put them above my wiring as long as I leave my 50mm air ventilation gap?

There will be 50mm pir under rafters too followed by plasterboard.

I didn't want to have that gap between the bottom and top insulation but can that cause issues?

thanks