Which studwall insulation?

[Shift]

While installing a new stud wall in my 1930's 3rd bedroom extension to make an ensuite I thought I would add some insulation but unsure which would be best. Stud wall is 89mm deep so was going to fit 75mm celotex. Would this be OK and help keep the ensuite warm or are there better alternatives
Also the floor that's above the carport needs insulating, joists are 180mm deep. I thought 50mm celotex at the bottom then 100mm thermal insulation roll so it's easier to get around pipes etc, would that be ok

 

[23vc]

Use rockwool acoustic type, not celotex for the stud wall.
For the ceiling with unheated space below, ideally PIR across ceiling joists and as much depth as you can get using loft roll wool type between joists