PSA exam

No worries. The SJT ultimately is one of those exams that you can't fully revise for as that's how it's designed to be. I think a month or two of revision is more then enough enough Try and not use too many different resources - I think two is a good balance, maybe three max. If you start using loads of resources, you'll find that they have conflicting answers for certain scenarios and you'll just confused yourself. The best resource is the mock that the SJT website has, and how you use it is up to you. I used passmedicine, oxford handbook for SJT and the mock to prepare, and attended a free SJT workshop run by my uni's med soc.
The main thing is to know the general gist of the different GMC domains. Then from that establish some principles to follow to make answering easier e.g. have a system for escalation - dealing with doctors and nurses are different. Remember patient safety is always first. Always try and to gather information first and talk to the person involved. Always try to maintain confidentiality where possible.
There's more principles but the above is just to give you a flavour. As you do questions and become more familiar you add in your own principles based on the GMC domains. Bear in mind this system may not work for everyone, but worked well for me and allowed me to score highly in the SJT!