The material below is simplified to a degree in order to make it easier to understand.
Currently UK aviation is governed by European Authority in safety aviation (EASA), which all starts with Regulation (EU) 2018/1139 the ‘Basic Regulation’. The Basic Regulation establishes a European Union Aviation Safety Agency and common rules in the field of civil aviation.
Regulations are found here.
The Basic Regulation is what is termed ‘Hard Law”, that generally means legal obligations that are binding and which can be legally enforced before a court. ‘Hard Law’ is, however, sometimes a little light on the detail of how to comply and is thus accompanied in many case by Acceptable Means of Compliance (AMC) and Guidance Material (GM). AMC & GM is termed ‘Soft Law’ and fleshes out ‘the Hard Law’.
Underneath the Basic Regulation are a number of other regulations which are also ‘Hard Law’, the most interesting to the recreational pilot are Aircrew (which includes pilot licensing), Air Operations and Standardised Rules of the Air or SERA. All of these regulations have annexes, which are again ‘Hard Law’ and this is where we find more detail.
Aircrew (Commission Regulation (EU) No 1178/2011)
Annexe I (Part-FCL)
Annexe IV (Part-Med)
Air Operations (Commission Regulation (EU) No 965/2012)
Annexe VII (Part-NCO)
SERA (Commission Regulation (EU) No 923/2012)
Annexe I (Rules of the Air)
Each regulations including its annexes along with the ‘Soft Law’ provide a fuller picture of the landscape and the details.
As examples, the privileges of the PPL and the experience requirements to apply for a PPL are found in Part-FCL (Flight Crew Licencing), whereas the requirement to carry a Personal Locating Beacon (PLB) are found in Part-NCO (Non-commercial operations with other than complex-motor-powered aircraft) and for completeness the definition of VFR and the meteorological conditions that constitute VMC and what the UK used to call Rule 5 (low flying) are found in SERA Annexe I, Rules of the Air.
Sound complicated, well it can be but then again no more difficult that trying to figure out an airways route using a standard paper chart and after a little practice what starts as 0100 OVC 100 slowly clears to 9999 NCD but probably never CAVOK!.