JB,
You need to start your studies with the Interntional Civil Aviation Organisation (ICAO), which was set up by the Chicago Convention of 1944. Basically, this sets out the safety rules for worldwide civil aviation and the principle that each State (another word for Nation) will allow various rights and privileges (called 'freedoms' in ICAO-speak) to every other State, provided that State is a member of ICAO and their aircraft and pilots are ICAO-compliant. In theory, ICAO transcends the National Aviation Authorities (NAAs) set up by each State, or groupings of NAAs such as JAA or the new European Aviation Safety Agency (EASA). Where States choose to vary from ICAO Standards and Recommended Practices (SARPS) then they must publish 'differences' so that other States understand what is different about aviation in a particular State.
Hopefully the above will give you some more material to research. For the UK, look at CAA-published document, the Air Navigation Order (ANO) and a National Air Traffic Services (NATS) document, the UK Aeronautical Information Publication (UK-AIP), all available on-line at no cost to the end-user (unlike ICAO and JAA documents, which cost a lot to obtain).
Cheers,
TheOddOne