It's a fair question, but with no easy answer - it's never been tested in court and CAA has declined to ever give a definitive answer.
The actual wording is
"The aeroplane shall not be flown over any assembly of persons or over any congested area of a city, town, or settlement"
The add on condition is
"Except when taking off or landing at a licensed or government aerodrome in accordance with normal aviation practice"
I'd suggest as a general rule of thumb, if there are enough people to get annoyed by your noise (at-least when you are low enough for them to read your registration
), or it's painted yellow on a 1:500,000 chart - it probably falls within the meaning of the act. Frankly all it's doing is forcing you to follow the sort of good, polite flying practice that anybody should be following regardless - it's not a significant restriction.
It's also very sensible to come in high and fly a glide approach if landing over any form of conurbation - but that I'd apply to anything with only one engine, regardless of the paperwork.
G
N.B. FlyStim - Switzerland came to their senses about two years ago I believe.