An insurance policy is a contract and your rights as the holder of the policy will depend entirely on what is written in the contract and on any endorsements which may be added to it.
Many people are chronically under-insured.
Everyone who owns and drives a car on the public road must, by law, have at least third party insurance cover. This covers your liability for injuries to other people, their property, and their cars, caused by the use of your car while it is on a public road. If you run a business you are legally required to have insurance to cover you if one of your employees is injured or ill as a result of working for you. The law also requires that you exhibit a certificate of employers' liability insurance at each place of work. However, if all you are doing is employing a home help or cleaner you do not need this kind of insurance.