On Sun, 13 Sep 2009 21:36:34 +0100, a certain chimpanzee, "David WE
Roberts" randomly hit the keyboard and produced:

I am in England.

According to my information the maximum area before building regs comes in
is accompanied by a maximum height.
Logical, really - a single storey light house in your back garden might
unreasonably annoy the neighbours.

e.g. from http://diydata.com/planning/planregp...ning_rules.php "It is
not more than 3m high for a flat roof, or 4m with a ridged roof."
Don't think this site is fully up to date, though.
http://www.planningportal.gov.uk/eng...315233153.html looks
a better bet.
"#Outbuildings and garages to be single storey with maximum eaves height of
2.5 metres and maximum overall height of four metres with a dual pitched
roof or three metres for any other roof.
#Maximum height of 2.5 metres in the case of a building, enclosure or
container within two metres of a boundary of the curtilage of the
dwellinghouse.
#No verandas, balconies or raised platforms."

Also, 15m^2 max. if within 0.5m of a boundary unless built from mainly
non-flammable materials.

As I will be building within 2m of the boundary I am limited to a maximum
height of 2.5m - 0.5m higher than maximum fence height.

Planning and Building Regulations are two completely different things.

The height requirements are for planning rules on permitted
development. Building regulations exempt any single-storey building
not containing sleeping accommodation with a floor area of no more
than 15m^2 anywhere and of any height, and any building of less than
30m^2 and of any height if constructed substantially of
non-combustible materials or more than 1.0m from a boundary.

I suggest you go back and re-read the pages you linked.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"