Appreciate the help though texture isnt going to offset a 10mm gap. Will work for the mid bit tho.

Ah yep makes sense. Plasterboard is already installed at a tilt however so will need to measure, shim the far side then plaster until level.

The one more central to the room (5mm offset in the diagram) isn't so bad however, the one at the edge of the room is and will mean the architrave will be off as well if not adjusted.

Joists should of been checked beforehand but time is tight so mistakes were made.