Alrighty. I just need to remind you that its not hard work that pays off its effective work that pays off. With further maths, the best advice I could give you would be to start at least one module over the holidays, start writing up your reference book early, every time you finish a module/core topic summarise the chapter related to the topic. Then throughout the year you can add or remove anything you need/dont need. If you work consistently throughout the year you will do well in further maths (and your other subjects). Time management is the key ^_^ Good luck.
To get 40+ you will need to average A+ throughout the year... SACs make up 34% and the exams make up 66% (exam 1-33% and exam 2- 33%)
When it comes to SACs ranking is quite important, so try to be ranked 1st or 2nd in your school in further maths, but I wouldn't worry too much about ranking, just focus on doing your best, and as I mentioned earlier aim for about A+ in all SACs and both exams and you'll get 40+.
I wouldn't advise you to do too many practice exams either, about 10 should be enough, you need to make sure you understand everything and that you avoid making silly mistakes (especially in exam 1).
Hope that helps clarify things for you, if you have any questions feel free to ask