Got DDD in My A-Level Mocks - Need Serious Help with Revision

Hi everyone,
I recently got my Year 12 mock results back and ended up with a DDD, which has been really disheartening and honestly really disappointing. For GCSEs, I attended a state school - and although my grades weren't perfect, I didn't think that I was underperforming. However, now I am studying A-Level English Literature, Maths and Computer Science at a Grammar School and everything is so much different!
I just wanted to provide some context for this, for my Maths paper we only did one paper but it had Pure Maths, Mechanics and Statistics. For English Literature, we did a paper which was split into Hamlet and Poetry (which we had only really just started as a class). For computing, we did both papers but I have yet to receive Paper 2 which might push my grade up but looking unlikely.
My school has been quite harsh with the boundaries for the tests, I know in my English Literature exams they were raised up a grade. However, even if they are raised I'm still dissatisfied with the result and wanted to ask you how to revise. I feel like the way that I am revising, I feel confident about what I am doing but as soon as I go into the exam, everything disappears out of my brain and I can't interpret questions correctly.
For Maths, I am studying the Edexcel course. Same with English Literature, and my set texts are Hamlet, A Streetcar Named Desire, NLMG, Frankenstein and the two sets of poetry (and the coursework). For my computer science, I am studying the AQA course, and I particularly struggling with Paper 2.
I am open to any kinds of revision.
Thanks in advance for any help! 🙂
Lily

I don’t do English Literature or Computer science, however for maths, my biggest advice for revision would just be past papers and YouTube.
In my opinion, doing lots of past papers exposes you to a variety of different questions, some of which may repeat in some form or another. At first, naturally, you will make mistakes, however, absolutely make sure to go over these mistakes by either asking a teacher, or looking on YouTube, instead of getting frustrated and moving on. I also find that I often learn more from making a mistake in a question, than I do purely focusing on theory from a textbook.
Another big thing that helped me was redoing past papers, as it not only boosts confidence when you get a higher mark, but it ensures that you learnt from your previous mistakes. There are lots of past papers out there, both from Edexcel, and other exam boards that, specification wise, are all fairly similar.
Finally, I found that using ChatGPT when I was completely stuck could sometimes be useful, even if explaining a concept, as you can sent screen shots of questions to ChatGPT which speeds things up. It’s not the most reliable, so it terms of maths, take what it says with a pinch of salt, but often it does help.
Here are some links to resources that I have found particularly useful for A-Level maths:
1) https://youtube.com/@tlmaths?si=GhU_l6PvaCBHyJ6O (tlmaths on YouTube - videos on pretty much every topic)
2) https://www.physicsandmathstutor.com/a-level-maths-papers/ (pmt for all exam boards past papers)
I hope this all helps, feel free to ask any questions!
Ralph