Do I need planning permission to move the staircase?

Planning permission is not required to move a staircase. However, any interior structural works are notifiable to Building Control. When you move the staircase, you will need to create a new structural opening to be cut into the floor above which will then require trimming out correctly to support the stairs and retain the floor integrity. A structural engineer will provide you with the required compliant design and your designer will submit drawings and calculation to Building Control.