It depends on whether part of your home is predominately used for business: we say predominately because if any part of your home is used exclusively for business this can lead to being charged business rates and possibly capital gains tax when the property is sold.
HM Revenue & Customs see the expense of working at home as higher light and heat charges e.g. under their simplified expenses rules for the self-employed £26 per month is allowable if you work more than 101 hours at home per month.
However, you may claim a proportion of all property outgoings including mortgage interest or rent based on the amount of space used in your home and the time spent working at home.
Only mortgage interest can be included in calculations not the whole of your mortgage payments unless the mortgage is interest only.