In answer to 'Does anyone have first hand experiences to share?'
It probably works different in Scotland. I have the same problems as many of you , where to store tools, where to go and sit when it rains / make a cup of tea etc, so I went to the local planning office and asked ' I don't need planning permission to put up a shed do I?' .
To cut a long story short.
Planning permission & building warrant required.
Expert consulted (Richard who did the plans for my conservatory), he knows a mate who knows about rural buildings.
Experts mate writes to planning department and confirms planning permission required but not building warrant, however planning application should include structural engineers report i.e. may as well do all the work for a building warrant.
I do dimensioned drawings and a concept sketch & tell Richard to apply for planning permission for 'Woodland Bothy'.
Drawings passed to structural engineer.
Structural engineer comes back with impractical beam sizes and incorrect grade of timber specification. Sent back to reconsider . Sorted out in the end.
Long wait (10 weeks)
We can't have planning permission for a 'Woodland Bothy' (carries habitation connotations) but can have planning permission for an identical structure called a 'Tool and wood store'.
Planning permission arrives, however the fully stamped drawings have the main supports in the wrong place.
Decide not to make fuss, as building warrant is not required it probably won't be inspected in that detail.
Planning application £134
Richards fee £400
Structural engineers fee £200 (after extra time)
£734 + stress just for permission to put up a shed!
Adrian (disillusioned by red tape but now happy, although skint)