Recipe:
Read the Book (Thom book 2 : and it's only half of it).
Refrain from agonising about anything.
Take the examination.
If you're interested enough in aviation as a whole you will have retained enough information to pass, otherwise you are likely to fail.
There is no point working yourself close to hysteria about any of it - in truth, with all the PPL ground examinations, you need to be able to remember enough calmly to make you a safe pilot in practice: not cram enough to pass a ground examination. Basic understanding of the subjects is worth far more to you and to others in the sky and below it than cramming enough into short term memory to pass, and then forgetting most of it, or never understanding the principles in the first place.
I believe that virtually all aviators will have enough interest in the subject to retain the principles if they approach it calmly. As others have said, between now and 7th April is a long time: a calm reading of the Thom book (the half of it which refers to Aviation Law) will enable you to cover the examination syllabus with ease.
As ever, when coming to paper itself, basic (really basic) examination technique is a boon: i.e. read the question and understand it before attempting to select an answer!
[Altered to correct a typographical error, only observed after initial posting.]