Use of room for office, put the wife down for wages allowance, all them phone calls you make & purchase of mobile,
computer equipment, if you are not sure then get in touch with H M R C they are very helpful. Have you looked at a program for doing your tax on, it's called Tax Calc brilliant piece of kit once you get the hang of it. The cost is about £30.00 a year but it is tax deductable. it can be a bit of a minefield, hope this helps.

Rickster