For section A, we were told to design garden aids such as raised flower beds or garden kneelers because my teacher said it was unlikely that they would ask about tools, but maybe have one or two tools just in case.
To revise, we practised past paper questions and most of the papers ask pretty much the same questions each year so I think you should go through all the past papers so you know what kinda questions to expect. Also look through the mark scheme because the design questions in section B require pretty much the same answer each year.
A lot of the exam is common sense so I wouldn't bother revising too much since the exam is only 40%. That being said, I would probably look over any topics you don't understand so at least you have a general idea of what to write.
Feel free to ask anymore questions and good luck for your exams!