Bladesmanstan

Hi, so today I got a letter through the post indicating that I have been charged a penalty for a late tax return. The issue is I wasn't even employed or self employed in that quoted tax year: I was still in full time education. I really don't get why I have been penalised. The frustrating thing is when I try to appeal it states I need to file a tax return for the quoted year. When I try to file one it literally states "there is no history of employment so you don't need to file a return." I'm just going around in circles at this point.