Indeed occupancy is unlawful but, if its a summer house then the following applies:
The section below is the latest rendering of the Planning Act - October 2009. We have simply copied it at the moment, but we will translate it into everyday English - with examples - as soon as possible.
Permitted development
Class E
The provision within the curtilage of the dwelling house of —
(a) - any building or enclosure, swimming or other pool required for a
purpose incidental to the enjoyment of the dwelling house as such, or
the maintenance, improvement or other alteration of such a building or
enclosure; or
(b) - a container used for domestic heating purposes for the storage of
oil or liquid petroleum gas.
Development not permitted
Class E.1 Development is not permitted by Class E if —
(a) - the total area of ground covered by buildings, enclosures and
containers within the curtilage (other than the original dwellinghouse)
would exceed 50% of the total area of the curtilage (excluding the
ground area of the original dwellinghouse);
(b) - any part of the building, enclosure, pool or container would be
situated on land forward of a wall forming the principal elevation of
the original dwellinghouse;
(c) - the building would have more than one storey;
(d) - the height of the building, enclosure or container would exceed—
(i)4 metres in the case of a building with a dual-pitched roof,
(ii) - 2.5 metres in the case of a building, enclosure or container
within 2 metres of the boundary of the curtilage of the dwellinghouse,
or
(iii)3 metres in any other case;
(e) - the height of the eaves of the building would exceed 2.5 metres;
(f) - the building, enclosure, pool or container would be situated within
the curtilage of a listed building;
(g) - it would include the construction or provision of a veranda,
balcony or raised platform;
(h) - it relates to a dwelling or a microwave antenna; or
(i) - the capacity of the container would exceed 3,500 litres.
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For Revision
Your House is a listed building.
If the fence, wall or gate, is next to a highway used for vehicles (a footpath is part of the highway) - over 1m height requires permission.
Where it is not next to a highway, any fence gate or wall over 2m will require permission.
Hedges or trees - to whatever height - do not require planning permission! (Even if they are next to a highway.) You will need to check that there were or are no restrictions on your property though: such as those that apply to 'open plan' estates.
There are restrictions however under the 1980 highways act >>>>>
Highways act 1980 - summary
Section 136. The Highways Authority may request a court order for pruning, if the highway is being damaged by the exclusion of the sun due to a hedge or tree.
Section 138. It is an offence to plant a hedge without the Highways Authorities permission.
Section 141. It is an offence to plant a tree within 15ft of the centre of the carriageway. This is subject to S64, S96 and S142.
Section 142. The Highways Authority may grant a license to a member of the public allowing them to plant and maintain vegetation near the highway.
Section 154. The Highways Authority may serve a notice requiring the pruning of vegetation which obstructs the passage of vehicles, the view of drivers, the light from a street lamp, etc to be cut. This section also covers the ordering of the removal of dangerous trees which may threaten the users of the road. The work should be carried out within 14 days.
Patios & Driveways & Garden Buildings/Structures
If you live in a house! (There are different rules for flats and maisonettes)
If you live in a house, there are no planning restrictions for any size area of patio or other hard standing - providing that it is for 'domestic' purposes - for the rear garden. You can concrete the whole lot over if you want.
However, if you build a new driveway which will cross a pavement or verge, then you will need the permission of your council's Highways Department.
From 1 October 2008 there are new rules for householders if you want to pave over your front gardens.
You will NOT need planning permission if a new driveway uses or porous surfacing which allows water to drain through. This will include surfacing such as gravel, shingle, permeable concrete, block paving or porous asphalt. Also if the rainwater is directed to a nearby lawn or border to drain naturally. HOWEVER - If the surface to be covered is more than five square metres planning permission will be needed for laying traditional, impermeable driveways that do not control rainwater running off onto roads.
You will also need Highways Dept. permission and possibly planning permission if you wish to make a new or wider access onto a trunk or other classified road.
You do not need Planning Permission for a garden shed or summer house **
or a swimming pool **
or tennis courts **
or greenhouse **
or sauna cabin **
or dog's kennel or other animal enclosure! **
or a garden pond **
You will need permission for a domestic oil storage tank - or other such container - if the capacity is more than 3,500L. or if it is more than 3m high.