You are not entitled to deduct any of the interest on money borrowed to buy your home if, for convenience, you use a home study to undertake work usually done at your place of work. Similarly, you are not entitled to deduct interest if you do paid child-minding at home (unless you have set aside a special part of the home exclusively for that purpose).
In these situations you would not satisfy the interest deductibility test. This means you would obtain a full main residence exemption and so would not have to pay tax on any capital gain made when you sell your home.