According to the Immigration, Nationality and Asylum Act 2016, employers must carry out proper due-diligence to confirm any potential permanent, part-time, or temporary employee has the right to work in the UK before they can begin work.
Right to Work applies to any work experience or unpaid workers. All businesses are required by the Home Office to keep evidence of all the right to work checks they carry out, as well as checking the document provided is genuine and the applicant is its rightful holder.