The same is true indoors. Turning a spare bedroom into a working office is mostly about acoustics, power and light rather than furniture.
Building a garden studio properly
An insulated floor, walls and roof with a continuous vapour control layer, proper glazing and a small heating and ventilation provision are what make the building usable in winter and comfortable in summer.
Overheating matters as much as heat loss. Orientation, glazing area, shading and some means of purge ventilation should be decided at design stage rather than solved with a fan later.
Power, data and drainage
A properly designed and certified supply from the house, with adequate capacity for heating and equipment, is the correct route. Extension leads across a lawn are not.
Data can be run in the same trench, and if you may want a WC or tea point later, laying drainage while the trench is open costs very little compared with digging it twice.
Planning limits and internal alternatives
Outbuildings often sit within permitted development, subject to height, position and the proportion of garden covered, but designated areas, listed buildings and estate covenants can change that.
Where a garden building is not viable, converting a garage or fitting out a spare room with acoustic separation, joinery and proper lighting achieves much of the same result for less.
Common questions
Do I need planning permission for a garden office?
Often not, if it meets permitted development limits on height, position and garden coverage, but listed buildings, designated areas and covenants can change that.
Can it be used all year?
Only if it is insulated, airtight and heated as a small building rather than as a shed. That is the main difference between products on the market.
Can I have water and a WC?
Yes, with drainage designed and connected properly. Laying it while the power trench is open is far cheaper than retrofitting.
Is a garage conversion cheaper?
Usually, because the structure and slab already exist. It needs the floor, walls and roof upgraded to habitable standards.

