Hey!
I would say you are allowed to do another text, but here are a few reasons why you shouldn't do another text:
- You said you would rather do a poem, but in AOS or any other module you'll have to study ~6 poems (I assume each poem will have similar themes and might suit different questions) and do all the analysis yourself.
- Studying a new text is a lot of effort for a very short amount of time before trials! You may as well push through with the text you've already been prescribed at school. Maybe check out some of the English notes
here to see if you can find some notes on your text!
- Your teachers will be your markers and you don't really know what they'll think when they get an essay with a totally different prescribed text to what they've taught. Adding to this, you probably won't get a lot of support from them content-wise if you change texts.
- You don't need to have a prepared essay before the exam!!
As for doing a "Standard" text, there's no set Standard/Advanced text in the AOS - I know schools who did the same text for both levels of English so no text is particularly easier than another one.
Pleaaaaaase don't change texts!! It's so much easier to continue with the one you already have, no matter how crap you think it is. You have less than half a year until you'll be done with this text anyway!
Best of luck :-)