Book your theory test - The official site. To book you will need your driving license number, and a credit/debit card. Currently, the theory test costs £31.00.
Book your driving test - To book a practical driving test, you must have a valid theory test pass certificate. When booking you will be asked to provide your theory certificate number, the date that you passed your theory test, your driving license number, and your date of birth. Again, you will need to pay when you book.
The practical test costs £62 on weekdays, and £75 for weekend tests (they have to pay the examiners overtime)
If you don't want to book online, you can also do it over the phone. The Driving Standards Agency's booking service phone number is 0300 200 1122
Pass Plus - Information for drivers who've passed their test but want to take their training further.