thanks for that Brian, the garden shed, is large at 4x5metres but will be all wood not fixed down, so i presume it will be excempt from planning.
next thing that I will have to query is what does a poly tunnel fall under.
I guess we have picked up an answer through my OH selling houses, in fact I asked her. She said that if it is a permanent structure it needs planning. That is, as she explained, walls fixed to a permanent base or embedded in the ground. A temporarily structure like a wood or metal shed, pergola or greenhouse does not need permission. It is a question she has been asked often by people wishing to put up some kind of garden shelter, garage or the like who are as often as not trying to avoid needing to wait for permission.