OMG literally the same thing happened to me.
We did nothing in year 10, and in year 11 we got a teacher who only has an ICT degree. So we had only been doing the CA's all this time. We have only covered: Networks, Software and Hardware, and Databases.
I knew were not going to be taught everything by the time the exams start, so i got this revision guide:
https://www.amazon.co.uk/Revision-Computing-Computer-Systems-Programming/dp/1444193848It has some extra stuff about random topics, but just focus on the topics you've been taught.
Do you have the blue gcse computing textbook by Susan Robson? If you do - look at the topics in there, and then use the revision guide to learn the information, because it's simplified and easier to understand
Or have you been taught with another textbook?
I wish you the best of luck
Btw, if you don't mind me asking, how did you do on your a453 and a452?
If you did well, i wouldn't worry about the exam so much, as it's only 40%