Allowable expenses for Isle of Man sole traders are the costs of earning the profit, not the costs of living. The Assessor of Income Tax sets that out in GN 1. This page does not guess a gov.im media address for that note. The current rates and allowances, which sit beside the expense rules, are on the Assessor's rates and allowances page.
Allowable
Allowable expenses are the costs of the business, as the Assessor describes them in GN 1. Materials and tools for the work sit on that side of the line. If you drive for work, keep the business miles with the other records. See How does mileage work for Isle of Man sole traders?.
Not allowable
Private living costs are not allowable expenses. GN 1 is the Assessor's note on the difference. A UK expense list is not the Isle of Man one.
Estimate the tax on profit after allowable expenses with the Isle of Man tax calculator.