DIY - Under the stairs

Don't have any pictures prior to starting this job, but needless to say it was a mess... first problem was the fact that underside of the stair case was covered with thin ply wood, but the joints were covered with skrim (the self adhesive skrim, see pic of the dining room ceiling) which is used before plastering, not for the purpose it had been used, so i had to remove everything. the walls were covered with plaster board but were stuck on with plaster and nails rather than using proper dry-lining adhesive. So all that had to come off, and the plaster underneath was a mess, so that has to come off too.

Ive already built the wall at the bottom of the staircase and boarded it ready for skimming, i'll use special plaster board screws to attach the plaster board, not a good idea banging nails in when the plaster work above the staircase has already been done, i'd probably end up making cracks everywhere...

As you can see the walls still need floating with a motar mix, however, the new door casing does no protrude far enough away from the brickwork, so i will glue and tack a 1/4" x 1" peice of wood around the frame giving me a better chance to float it out straight.