I don't think you can be ready for 4 unit, after the prelims easy questions, ( in the old paper Q1 -5) you're screwed. Half the stuff in the papers I have never seen before in my Maths life.
Anyone ready for the 4 unit test? I still haven't touched harder 3 unit or mechanics opps. Getting conics down atm tho :P I heard you only need to be in the top 90% to get scaled up in 4 unit?