http://www.2pass.co.uk/auto.htm
Driving an automatic car on your driving test is allowed, although after you have passed your driving test, that is the only type of car you are licensed to drive. If you ever wanted to drive a manual car you would have to retake your test in a car with manual gears.
Learning to drive in a car with automatic gears (transmission) is a lot easier than driving a car with gears because there is no clutch pedal to operate. So the left foot should not be used at all, you should use the right foot to operate the accelerator (gas) pedal and the brake pedal. This makes it a very popular choice by learners who find it difficult to get used to the gears and clutch when driving a manual car or for older and disabled learner drivers. After you have selected drive with the gear selector the automatic gearbox changes the gears for you. There are certain situations where you may need to select a specific gear to help control the car or to lock the car in a certain gear stop the car changing up for example when driving down a steep hill. You will also need to use the handbrake and brakes a lot more because of the cars creep, this is when the car will start to move after you select a gear.
When driving an automatic car the usual layout for a gear selector is:
P - Park - this locks all the gears and should be used when stationary.
R - Reverse
N - Neutral - No gear is selected.
D - Drive - This is used for driving forward.
1 - First Gear.
2 - Second Gear.
Note: Some automatic cars may have extra selections than those shown above.