In the UK, you need to
- Be >=17
- Apply for a Provisional Drivers Licence
- Sit and pass a written (done on a computer these days, though) theory test
- Sit and pass a 40 minute practical test which is apparently the hardest in the world. If you fail, the law says you have to wait a minimum of ten working days before you can try again.
When you're learning, you have to have red "L" plates on the car and you have to be accompanied by someone who is >=21 and has held a full driving licence (i.e. passed their test) for at least three years.
But once you pass your test there is no restrictions on having passengers or where and when you can actually drive.