UK: KS3 essment: Is this Cheating?

Hey, I live in Britain and I am taking a year 8 English essment on Friday. Its nothing big, just a little test to see if we should be in the group were in. We have to basically re-write a bit of Frankenstein and either make the experiment a success or failure using Pathetic Falacy and stuff. I'm 13/14 and so this won't be super hard. My teacher says we have to have a maximum one or two sides of paper to write our mini story opening on. I am a horror girl and so I want to make my essment horror! But I have had serious writers block for the past few months, it won't go away and I was really scared about my essment. If I do the work at home and just swap the work I did at home with the work I did at school, is it cheating? I didn't talk to anyone while I wrote it and I didn't go on the internet to do anything either. I just typed up three sides of paper. I know I did too much but I really tried hard and I still have writers block but I managed to write a bit. So, is it cheating if I did the work at home instead of doing it in the clroom? I mean, I did it, nobody else did so theres nothing wrong is there? Please help x Should I just take the sheet and explain to my teacher I have Writers Block or something? Please help, I'm stressing because I don't to get moved down to a lower group....