This process has to be completed in strict order. The theory and hazard perception tests have to be passed on the same day. After the pass certificate has been awarded you are then eligible to apply for your practical driving test.
The Show me / Tell me questions form a part of the practical driving test and are asked at the beginning, before you move off.
The theory test needs practice before you take it. I recommend that you buy a set of up to date cd/roms containing all that you will need to pass both the theory and hazard perception test at the first attempt.
Apps are available for mobile devices which are also helpful. Many pupils of mine have found the app on their mobile very convenient to practice the theory test whenever they have a few spare minutes. Certainly practicing for the hazard perception test is easier on a larger screen.
A lot of people are nervous about taking these tests. Keep practicing until you have been successful on your last three successive attempts. It is better surely to practice a lot in private and pass the test on the first attempt rather than keep on paying those test fees!
The practical driving test should not be attempted without first making certain that you are up to standard on all of the required manoeuvres and that you are a competent and confident driver.
Professional tuition is always the best method of preparation for the practical driving test. No-one knows better how to teach you to manage the local traffic conditions, junctions and not forgetting of course, those manoeuvres, than your experienced local instructor.
The Show me / Tell me questions are an integral part of the test these days. At the beginning of your test you will be asked two of them. Do not worry about this process unduly. I will have shown you around the car well in advance and prepared you for this. Expert mechanical knowledge is not required.
These questions help you to know the basic checks that should occur regularly on your car anyway, and a few ways of knowing in advance if something is beginning to go wrong with the major systems, as well as effective use of your cars ancillary controls.
Some people are taught to drive by relatives or friends which is legal; but even then I would still recommend at least taking an assessment lesson before attempting the test.
The advice of a professional is worth the cost. The driving test is far too expensive an experience to want to repeat.