Ask a UK public authority for recorded information under the Freedom of Information Act 2000.
UK: FOIA 2000 / ICO.
EU: not FOIA — use your member state’s access-to-documents law or Reg. 1049/2001 for EU bodies.
You do not have to mention the Freedom of Information Act. A request is valid if it is in writing, uses a real name, gives an address for correspondence (email is fine), and describes the information you want.
This is not a GDPR data-subject request. If you want your own personal data, use the data subject request form.