I own a small shop in London. To increase showroom space I would like to open up my cellar (which is dry!) I currently have access to the cellar from the back of the shop. This is not ideal as it is hidden from view and not very welcoming to customers. I would like to put a staircase in at the front of the shop - well lit by the front window. The basement ceiling height is 2.2m What I need to know is: Is this feasible? How much space would the staircase take up? How big would the whole in the floor be? How much? How long? Do any (reputable) builders work over christmas? (shop is closed for about 10 days) Would these reputable builders charge a premium for working at this time? Any guidance would be appreciated.