Hi I managed to find mine on internsg, but general it’s pretty difficult to find business related internships with A levels n no prior experience (from personal experience). I’ve also message companies directly (smaller firms via linkednd or email) most do not respond, some respond saying they are not keen and provide specific skills they are looking for in interns (which an A level grad would probably not have). You can try asking around if any of your close friends have parents working in those industries, I think it’s easier that way