Choosing the construction
Choose around the shed, not a postcode assumption
Wareham sits within a varied landscape, so the building and the individual plot matter more than a broad label for the town.
Heavier workshops
A rigid concrete slab may be the sensible starting point when the supplier calls for full-area support.
Changing garden levels
A raised frame can create the required level without building an unnecessarily deep slab across the whole footprint.
Lower-excavation option
Ground screws can be considered where the building can sit on a properly planned support frame.