There are nine exams (Theoretical Knowledge Examinations) which must be passed before the flying skills test can be taken. These are multiple choice exams which are taken at your training school using a computer. The exams are timed. The pass mark is 75%. You will receive the result immediately after taking the exam
Register on the CAA Portal
You must set up an account with the CAA to register to take the exams. Do this before you even start studying. Your training school with receive a notification that you have registered, and make sure everything is ready before you take your first exam.
When you are registering, under the "Your Services" section, select "Private Pilot Theoretical Knowledge e-Exams"
Studying for the Exams
Each student may find a different method of studying works for them - do whatever works for you. Most start by reading the Pooley's book relevant to the exam, then quickly move on to using one of the online question bank providers (such as EasyPPL) to test how much has sunk in, and where the strong and weak areas are. EasyPPL also explains answers to questions you have got wrong, which ends up being a good way to target your weaker areas.
Once you are scoring 90%+ consistently on mock tests, you should be ready to sit the exam
If you feel you would benefit from face to face (in person or via Zoom) tuition, there are freelance ground school instructors who can help. For example richard@championflightraining.co.uk in the Surrey/Kent/Sussex area
Pooley's books (also available as E-books )
Timing your study
From the time you take your first exam to the last one must be within 18 months. You must then complete your flying training within two years after taking the last exam. For most this is a reasonable schedule, but if for any reason you have a long interruption in training, keep this in mind, as if you exceed the 18 month gap you must take them all again. The CAA is proposing to relax the criteria such that only the exams which are more than 18 months old "expire", but as of 2024 that is not the case
Your flying school will usually required you to pass a few exams before your first solo, then another few before first solo navigation; the remainder must be completed before you take your flying skills test
This means you can think of the exams as falling into three groups. Typically a flying school might divide these up as follows:
Group 1 (before first solo)
Air Law
Operational Procedures
Human Performance
Group 2 (before first solo navigation)
Navigation
Meteorology
Communications
Flight Planning and Performance
Group 3 (any time before you complete)
Aircraft General Knowledge
Principles of Flight