You need Employer’s Liability cover, unless the person is a mentioned family member. The following employees are excepted: husband, wife, civil partner, father, mother, grandfather, grandmother, step-father, step-mother, son, daughter, grandson, granddaughter, stepson, stepdaughter, brother, sister, half-brother or half-sister. It is a CRIMINAL (not Civil) offence to employ someone without having this insurance in place. Your policy must cover you for at least £5 million and come from an authorised insurer.
The fact that the Health and Safety at Work Act excludes domestic staff from the Act does not mean that one does not need insurance for them; it is provided under most people’s contents cover instead.
Although there is no certain definition and each case has to be considered on its own merits, domestic service is likely to include the provision of basic personal care, personal services or other domestic help provided to support an individual’s needs including home care and other domestic tasks. Factors which would tend to suggest an employee is not a domestic service provider include;
Where their employment includes tasks that are not ordinary domestic service, such as complex healthcare activities (eg operation of life support or palliative care equipment).
Where the task(s) require specialist training including qualified trained healthcare professionals. Examples of specialist training may include, for example, training in people handling tasks or dealing with behavioural issues.
See here for more on this: https://www.hse.gov.uk/foi/internalops/sims/pub_serv/071105.htm