You say, "Its an assignment from december and it has recieved a mark". Did you mean "hasn't", perhaps? I ask as you then explain that "there was an issue with the file" and "if they found a way to get the file uploaded", implying that no-one had (at the time) reviewed its contents. That being the case, it's difficult to see how "it has recieved a mark". Anyway...
You then reach the bizzare conclusion that the reason they're having trouble with the file "stems from me using AI". You also say that "The IT department have raised it and its a support ticket now but now its out there." However, you've said nothing about what's actually happened beyond that. Has
anything further happened? Is anyone apart if IT aware of your confession?
You say, "After dense research I can see AM is serious and im 90% getting kicked out." What
specifically have you read in the university's policies or procedures which has led you to this conclusion?
Have you read Nottingham's
Academic Misconduct Procedure? It details many potential penalties, other than simply a termination of your studies.
Do you know whether the Academic Misconduct Officer determined your case meets the criteria for a Desk Based Approach or to hold a School Academic Misconduct meeting? Do you know if the case has been referred to the Academic Misconduct Committee?
Being blunt, you need to stop catastrophising and start thinking and behaving like the lawyer you've said you want to be. Clarity of thought is key. So stop jumping to conclusions as to what you've decided your fate will be, and stick to the cold, hard, facts. Has an Academic Misconduct Officer even been
assigned to your case? Or is your imagination ten steps ahead of reality?