Teacher forcing me to take an extra language

I'm in year 10, and recently a teacher asked if I'm fluent in Persian, which I speak at home with my parents. She said she'd sign me up for Persian GCSE and I'd have mocks in less than a month. Problem is, I can't read or write Farsi since I never went to Farsi school. I mentioned this, but she brushed it off, saying I could learn.
I'm worried it'll be too stressful, especially with my other mocks coming up. I don't know when the Persian mocks are, but it's cutting it close. Is taking another GCSE really worth potentially damaging my performance in other subjects?
I told my teacher I didn't want to do the mock or the GCSE because it might affect my other subjects. She didn't seem to care about that, just wanted me to give it a shot. Even said not to bother studying for it.
I don't want the added stress of an extra language exam during the same week as my other mocks. I suggested just doing a practice paper to show my skills, but she declined all my reasons to get out of it. I don’t want to cause a scene, I just want to see if it is even worth it and if it isn’t how do I get out of situation so she can just let it go??
What should I do?

I'm in year 10, and recently a teacher asked if I'm fluent in Persian, which I speak at home with my parents. She said she'd sign me up for Persian GCSE and I'd have mocks in less than a month. Problem is, I can't read or write Farsi since I never went to Farsi school. I mentioned this, but she brushed it off, saying I could learn.
I'm worried it'll be too stressful, especially with my other mocks coming up. I don't know when the Persian mocks are, but it's cutting it close. Is taking another GCSE really worth potentially damaging my performance in other subjects?
I told my teacher I didn't want to do the mock or the GCSE because it might affect my other subjects. She didn't seem to care about that, just wanted me to give it a shot. Even said not to bother studying for it.
I don't want the added stress of an extra language exam during the same week as my other mocks. I suggested just doing a practice paper to show my skills, but she declined all my reasons to get out of it. I don’t want to cause a scene, I just want to see if it is even worth it and if it isn’t how do I get out of situation so she can just let it go??
What should I do?

I did French and German GCSEs way back in the dim and distant past. My recollection is that GCSE test your reading, writing, listening, and speaking skills.
If you can't read or write Farsi then you're not going to be able to do the reading or writing components.
I had a look on the web for previous years' assessment material for GCSE Persian. From that it looks like you'll need to be able to read Farsi to do the spoken and listening components -- for example, on a sample "listening" paper I looked at, some of the questions are written in Farsi and you are required to write the answers in Farsi. Likewise you will need to be able read Farsi to be able to do the "speaking" assessment.
If you don't want to do take this extra GCSE and the teacher won't listen to you, then you need to ask your parents to talk to the school.
In the worst case scenario where your school obliges you to do the mocks, you'll just need to understand what the rules are around leaving the exam early. But it seems like a waste of time having to attend the mocks if you won't even be able to understand large chunks of the question paper.

Thanks for the help! I was thinking of talking to the teacher once more today alone but I just received my mock time table and the persian mock is on it? I feel like cancelling now is going to cause them so much trouble as they've probably just got it official. I don't know I'm worried about what the teacher will say again as she waw quite persistent last time in shutting me down.

I'm in year 10, and recently a teacher asked if I'm fluent in Persian, which I speak at home with my parents. She said she'd sign me up for Persian GCSE and I'd have mocks in less than a month. Problem is, I can't read or write Farsi since I never went to Farsi school. I mentioned this, but she brushed it off, saying I could learn.
I'm worried it'll be too stressful, especially with my other mocks coming up. I don't know when the Persian mocks are, but it's cutting it close. Is taking another GCSE really worth potentially damaging my performance in other subjects?
I told my teacher I didn't want to do the mock or the GCSE because it might affect my other subjects. She didn't seem to care about that, just wanted me to give it a shot. Even said not to bother studying for it.
I don't want the added stress of an extra language exam during the same week as my other mocks. I suggested just doing a practice paper to show my skills, but she declined all my reasons to get out of it. I don’t want to cause a scene, I just want to see if it is even worth it and if it isn’t how do I get out of situation so she can just let it go??
What should I do?