The GOV.UK website states that you must get Employer's Liability (EL) insurance as soon as you become an employer - your policy must cover you for at least £5 million and come from an authorised insurer. It is becoming increasingly complex as to whether or not a person or company employs another person. Issuing a contract of employment is no longer entirely necessary for you to be an employer. MRSL Enterprise can help you to understand the rules on this.
Employer's liability insurance is there to protect you and your business against compensation costs, should an employee suffer an illness or injury as a result of their employment with you. This is the one insurance of the three highlighted here which is required by statute.
Often Employer's Liability insurance is purchased as a component of a Commercial Combined Insurance package that covers all of the property and liability risks of a small business.