The first step to getting on the road is to get a Provisional Driving Licence. An application form (Form D1) can be obtained from your local Post Office but you can also apply online from the 'Direct Gov' site.
Applying for your licence online requires that:
You are a resident of Great Britain
You meet the minimum age requirement
Your eyesight is of the required standard
You are not currently prevented from driving for any reason
You can pay by Mastercard, Visa, Maestro, Electron, Delta or Solo debit or credit card
You have a valid UK passport or another formal form of identity
You can provide addresses of where you have lived over the last three years
Theory test
The next step is to take the theory test. This is made up of two parts: multiple choice and hazard perception. Both need to be passed for you to get your theory test pass certificate. Only once you have passed this can you apply for a practical driving test.
You can also book the theory test online from the booking section on the same site.
Booking your practical test
Ok, you have your theory test out of the way so when your driving has reached a suitable level, you can look to get your practical test booked. How far in advance you'll need to book varies depending on the number of other learners applying at the same time. You should not just go ahead and book the test before checking that a car will be available first!
An 'independent driving' section is now included as part of the practical test during which you will be required to follow signs to a particular location to see how well you deal without direction from your examiner.
There is now more detailed information on Independent Driving here.