I know you probably gave up on the idea by now, but this is for future reference, just in case you face a similar kind of dilemma. It's not about your personal moral views, but more to do with the implications of the conduct itself.
Plagiarism is basically fraud, the way schools and unis see it. You will get an instant FAIL, if not an expulsion, and it will stay on your report forever. That means other schools most likely will not accept you, and that may have grave consequences on your future employment.
The reason why schools take plagiarism so seriously is because it shows that you cheated them just to get a pass. No one will look at you kindly for that. If plagiarism is consensual, it's still plagiarism, but they will refer to it as a collaboration. And they will still treat it the same way as plagiarism, so it makes no difference whatsoever.
So please, whenever you have an idea for plagiarism in the future, I suggest you find a nice brick and beat yourself over the head repeatedly until the thought goes away. It's all for the best. You WILL NOT get away with it, as the academic police in my uni tells me every single fucking time there's an assignment, no matter how little and insignificant it seems.
I'm sure that in this case, your teacher will be more lenient when it comes to marking your roughly-done work. The fact that you've explained it, and that you've tried to do something to replace the work, should really be a great help to you. Best of luck!