You must get Employers’ Liability insurance (ELI) as soon as you become an employer (work experience counts as employing a person even if you don't pay them) - your policy must cover you for at least £5 million and come from an authorised insurer.
This falls under the The Employers' Liability (Compulsory Insurance) Act 1969.
We are unable to approve a work placement without this. Please reach out to your Work Placement Coordinator to discuss if you need further guidance on this.