I have found this BBC refence to the smoking ban
BBC NEWS | Magazine | Where can you smoke once the ban starts?
It states-
But smoking rooms can be provided in "any premises where a person has his home, or is living permanently or temporarily", such as hotels, care homes and prisons.
It appears that a way to overcome the ban is to have paying guests on the premises so that a smoking room can be allocated legally
PS a further newspaper item shows that my previous idea wouldn't be allowed
The Daily Telegraph asked the Department of Health: “Can I smoke...”:
...in my home? Yes - as long as you do not earn a living there.
... in my home if I invite friends there? Yes.
... in my home if a nurse visits? Yes - but the nurse can ask you to put out your cigarette out of courtesy.
... in my home when the cleaner comes? Yes.
... in my home if the builders are in? Yes.
... in my home if I have caterers to help with a party? No. It is now a workplace.
... if I work on a business plan alone at my home? Yes.
... if I invite a colleague to help me on the business plan at my home? No. It is now a workplace
... in a police car if I have been arrested? No. It is a workplace. A 7cm No Smoking sign must be displayed.
... in my car if I am using it for voluntary work? No. It is classed as work.
... on a bus? No. It is a workplace. A 7cm No Smoking sign must be displayed.
... outside my house? Yes - if the area does not have a roof. No - if it is enclosed, such as a public stairwell.
... in a smoking shelter, attached to my office? Yes and no. If it has a roof or canvas awning - yes. But if it also has walls or a door - no