The answer to the original question is:
Look at the Plane Spotters books to see where all the aircraft are based in Scotland.
Answer is big clumps at Perth, East Fortune and Strathaven - plus local strips all over the country, perhaps such as Longside or Culbokie.
The type of aircraft is also revealing: microlights and LAA-types (not all of which are home built).
Quite simply, flying an EASA light aircraft - basically the only type (other than some microlights, like Perth's Eurostar) for hiring - is expensive if you are doing lots of hours.
Buying a simple LAA-type and finding somewhere local with a few fellow flyers around seems to be the favoured solution.