it varies tbh. from what I have seen decision analysis had definitely changed since I last did it but abstract reasoning, verbal reasoning, SJT, and mathematics is the same.
verbal prep: just read and improve reading speed.
mathematics: practice gcse maths
abstract: do abstract tests
decision, learn the trend by doing questions (UKCAT website, Kaplan book, medify)
SJT: use commonsense
In general I would say use the UKCAT website & medify website, in addition to the kaplan book and whatever is the replacement to the 600 ukcat practice questions
when I did it previously, I did as many as I could in a day but restric the amount of questions you do.
I would say the hardest aspect of UKCAT is that you arne't allowed any water into the exam room (which is bad if you suffer from hydration issues)