Sips Exstension 2023

I am looking to build a Sips Extension to the rear of my property approximatly 38m2 with a flat or parapet roof type. The Exstension will comprise of a living room / kitchen dinner all open plan as per my attached sketch. I am currently in the planning stage and looking for costs associated with architect / structural engineer drawings ready to submit for planning. As part of my exstension I would like to reconfigure the current room layout along with moving my current straight staircase to create a lobby / hallway leading to the new extension and replacing it with a half turn staircase up to my loft conversion which was done approx 6 years ago.