How do I know if I am an employee?

A lot of your rights at work depend on being an employee (rather than being self-employed or a casual worker). For some people this is a complicated question.

The standard example is that of the chauffeur and taxi driver. The chauffeur is an employee or a worker. He is employed to provide his service and take you everywhere you want to go. The taxi driver is self-employed. He enters into a contract to take you to an agreed place for a fee. If you then want to go on elsewhere, the taxi driver either makes a new contract with you or refuses to take you.

Most of us are employees. If you are expected to turn up and work regularly, and cannot send someone else to do your work, you are an employee. It doesn't matter if you were never given a written contract.
If you are a casual worker, an agency worker, or some types of freelancer you are usually classed as a 'worker' rather than an employee. Workers have most of the same core rights as employees - they can take time off if their children are sick, but don't have a right to ask to change the hours they work. They also have the right not to be discriminated against or treated badly because they work part-time or because of their gender, race, colour, nationality, ethnic or national origins, disability, sexual orientation, religion or belief.

If you are paid to get a particular job done and technically you could send someone else to do it, you are self-employed. You do not have rights to leave if you are self-employed but obviously you can give yourself as much time off as you need. You do have the right not to be discriminated against and the right to work in a safe and healthy working environment.