The Industrial Injuries scheme provides no-fault tax-free benefits for an employee who has a personal injury caused by an accident at work or who contracts one of a list of diseases while working.
SSCBA , S.94 for accidents & Ss.108-110 for prescribed diseases

You are covered by the Industrial Injuries scheme if you are an ‘employed earner’, ie you are working for an employer. It doesn’t matter if you do not earn enough to pay national insurance (NI) contributions, or if you are too old or too young to pay them. Nor does it matter if the accident happens on your first day at work. What counts is that you are gainfully employed under a contract of service or as an office-holder with earnings.

You will not be covered if you are genuinely self-employed or you are a volunteer, unless the accident happens while you are doing specified types of voluntary work, eg as a special constable. There is a discretion to treat someone who is illegally employed as an empl