In the UK, you do not need a licence to listen to radio amateurs from anywhere in the world (or even in space - Major Tim Peake recently operated from the International Space Station and spoke to many people via amateur radio and was heard by thousands more!).
To transmit, you DO need a licence, for which you need to pass an examination. There are three 'classes' of UK licence, Foundation, Intermediate and Full, each of which give different access to radio frequencies and the power with which you can transmit.
The Foundation and Intermediate examinations consist of a practical and a written (multiple choice) examination.
There are many ways that radio amateurs can communicate across the airwaves, from simply speaking to each other, to Slow Scan (one picture takes several seconds to appear on the screen) or Fast Scan Television, many computer generated forms of transfer, and although Morse Code is no longer a requirement to gain a UK Amateur Radio licence, many people still enjoy the simplicity of making contacts using Morse.
Many life-long friendships have been made over amateur radio, sometimes between people on opposites sides of the world who have never met in person, but sometimes just between people in the same town.