After or during your reading up on knowledge then it would be time to do questions. I know people learnt from just doing questions. That is fair enough. Didn't work for me. But either way I would recommend the following resources:
Download the BIR SBA App:
http://www.bir.org.uk/media-centre/news/2014/november/new-imaging-single-best-answer-book-and-the-bir%E2%80%99s-first-app!/
I found these questions about the standard of the exam and the explanations were really good. I used to do them at work sitting in the back of MDT. I went through them again and again till I got them all right.
Very wordy questions and explanations. Too many words on a page make my eyes go funny but overall, this is a great place to start.
and
Both really good books and great explanations.
SBAs for the Final FRCR 2A (Oxford Specialty Training: Revision Texts)
Another very wordy book with long questions and explanations. I found the explanations very good. A book to do early in your training.
Get Through Final FRCR Part A: SBAs for the Modular Examination
Great questions pitched at a decent level. I would recommend that you get through this one early as it is a bit wordy.
The following books are ones to avoid!
FRCR: PART 2A - Single Best Answer (SBA) Questions for the New Format
I hated this book. The questions were not representative at all. There were some answers that were good to read through but I would not base how you do in this book as a marker as to how well you will eventually do. In honesty I would just avoid.
Succeeding the New FRCR Part 2A Exam by Asim Ahmed Afaq Edward Leen (2012-07-06)
This has to be worst book EVER! SPOILER ALERT!!! For whatever reason the answer to most of the questions is 'b'. The questions are so dumb. They just got a list off of Dahnert and made a question - 'What is not on the list'. In the explanations they were either a one line reference to the said list in Dahnert or no explanation at all...AVOID!
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