Reversing into a bay is easier to do accurately, but gives you harder access at the back. So, on the practical test, you may be asked to drive in FORWARDS then reverse out, like in a supermarket car park. Here's a second video.
Equally, you may be asked to REVERSE park. See my photopage for the stages of :
1. Lining up (distance from bay ends)
2. Turning (when to steer fully left)
3. Straightening (when, and to what)
Look here if it's hard to know which way to turn the wheel.
Some guidance on parking, and legal / private restrictions to it, can be seen in the motoring guide of a major insurance company.