There is a section of HMRC’s manuals that deals specifically with how you can view the rules for measuring profits of specific trades. The list includes over 50 different trades as diverse as

HMRC’s employment status service can be used to help ascertain if a worker should be classified as employed or self-employed for tax purposes in both the private and public sector.

The service

Directors and employees may be flattered and pleased that their employer pays for all their company car fuel, including fuel used for private purposes.
They will be less enthused when a Car Fuel

Whether you are self-employed or employed, if you use a car with a mix of private and business use you are required to keep a record of the business/private mileage split when making claims for tax