tacali

Looking for some advice. I have searched and searched the Internet. We were looking at building a garden room then when pricing ut up someone suggested putting a static caravan in the our garden (we have a very large garden). We were told by one person that we wouldn't need planning permission as it isn't going to be used as a seperate permanent living space. The next person at the council office was very rude and said we were lied to and we need planning permission and "we are on her radar" so not to put anything I the garden now and she wouldnt approve the planning permission even if we appled. I'm absolutely gutted we just need that extra space and this would of solved everything. Any clues on what we can do?