I am modular DTO. My DTO will not let you take the exams prior to 2 mock passes per subject. So again as others have aired, its strange you seem to have been put forward before being ready and cetainly without mocks in hand.
I over do it a tad, partly because of 2 reasons:
1. Because some resources do not really cover, explain or simply brush over the principles. To fill in the gaps I use a range of books, online material and BGS question banks. This I find helps with exam question familiarity, identify areas of weakness and iron out any creases, as it were.
2. Despite being quite academic, I am mildley dyslexic so utilise the sources, to understand and cement knowledge. However it may take me a little longer to absorb than some.
I truly wish the best with your future dont give up!