I passed my test 20 days back. I studied the book just once. To be honest left some parts of it in between. I would recommend you read it at least once. Its good to learn the first few chapters about history and invasions. It helps you understand the dates and kings. After that its very simply actually.
There are 24 questions of which 10-12 you may already know even before preparing for it like when is Christmas, Boxing day, capital cities of UK, how many pence in pound etc. These are straightforward. You would know the answers. Preparation is for the remaining 12-14 questions which you will need to learn and study.
There are online websites like
https://www.theuktest.com/life-in-the-uk-test/1 which have 48 sets with each having 24 questions. Last few days continously practice these sets. You should score at least 20 to 22 in these sets before the exams.
Questions may not be direct but can be rephrased. So you need to remember the question and the answer. I think good preparation is for 15-20 days everyday for an hour, also depends on the candidate and his brains. lol. For me I am no academician so I think I did for 20 days and all my free time I had downloaded free apps on the mobile and instead of playing games, I was doing the sets again and again.
All the best and dont worry. Its not hard at all if you prepare well. I got through my test in under 8 minutes and came out.