They're cavity batts and will be folded down or trimmed to meet the ceiling insulation - but I'm using proctor roofshield roofing membrane which doesn't require the roof to be additionally ventilated. £130 a roll but makes the roof construction a lot simpler.I'm not up on current insulation regs, but aren't those wads of rockwool going to impede airflow?
Wall plate is on the inner skin.Where is the wall plate?