Readers' forum: Property or business income?

My client has started a small bed and breakfast business from her home. She has incurred some costs in redecorating and buying new beds and other furniture televisions kettles and the like. She has also created some en suite bathroom facilities for a couple of rooms. To what extent if any can these costs be set against her income? I would imagine that there may be times when visiting family members use the rooms. Should I apportion some or any of these costs or can I claim them in full on the basis that personal use is incidental to the main purpose of generating B&B income?

Also can I claim a proportion of the mortgage interest my client pays? I also wonder whether I can at any point use the property allowance...