Speak to a teacher about your situation to see if you can arrange a 1-2-1 help session, it might not help a lot but it could give you insight (& some confidence) into your situation.
If you seriously just struggle with maths and visualizing numbers (etc) in general, then it could be worthwhile looking into whether you suffer from Dyscalculia, which is a common symptom of other things such as Dyspraxia.
Not a lot is going to change in a week. Revision, seeking helping, doing questions, etc- these are all a long term effort. Just do the best you can do.
You CAN get into university without maths (I did), but it depends on what you're applying for, your general talent and what your track record is like in other subjects.