I passed my PLAB 1 March 2018. I prepared for 3 months during my OBGYN rotation in housejob.
The PLAB examination is not about specialty exam , It is just a UK entrance Exam. I know that you know that but It is important to understand before you start preparing. So, If it is just an entrance exam It should not be hard to pass? Yes. If you study smartly. As it is entrance exam , They are expecting basic clinical knowledge from you. So, If it has been many years since you graduated , It can be bit difficult to recall all the basic stuff. If you have recently passed medical school/any other exam it is easier. In PLAB1 they are assessing basic clinical knowledge of house job level. They are not expecting you to know specialize knowledge in any subject. They will assess almost all basic subjects including Anatomy, physiology, biochemistry, pharmacology, Pathology, OBGYN, Medicine, Surgery, pediatrics (please check curriculum at GMC site).
The multiple choice Questions are of this pattern . What is your Likely diagnosis ? What is Gold standard investigation? What is first line of investigation ? What is first line of management? or some basic knowledge.
For example: A 65y male presented in A+E with central chest pain since last 1 hour and also complaints of SOB. (now relate the above questions with it) , Just giving you very basic example. They are not expecting you to know dose for streptokinase , but they would expect you to know dose for aspirin. They would expect you to know basic ECG findings for MI but they are not going to give you MRI to interpret.
They might ask you common bugs causing chest infection in newborns but not expecting you to memorize all classes of viral infections. They might ask you findings of ectopic pregnancy but not asking guidelines of ectopic pregnancy. You may check any sample questions on GMC site.
You should read some revision notes for basic knowledge , there are many concise notes available in market. You should practice MCQs as many as you can from different sources like 1700 MCQ by khalid, Unity , Plabable etc. You should try to do some timed MOCKS before Exams (either buy them from sites/ free from online sources)