Booking your theory and practical driving test should only be done by the person taking the test and through the official .Gov website.
The prices are:
Practical test: £62 weekday; £75 weekend.
Theory test: £23
Do not use resellers to book a test. You run a high risk of being scammed and losing your booking.
During the practical driving test you will be asked a ‘show me’ question and ‘tell me’ question. Get either one or both of them wrong and you will score a fault.
You can find the show me tell me questions here
Its useful to know how the examiners will be marking you. There is so much disinformation on social media.
Here is the official examiners guideline to a driving test
It can also be useful to know what type of faults are recorded specific to your test area.