I agree, go and have a calm word with the local council and see what you can do. My garage is technically a shed, as it is just inside the size for a shed and therefore didn't need planning permission. My shed is 24 feet by 11 feet. Talk to the council calmly and see what you can do without planning permission and they should help you. Be open and explain what you are doing and why, and what benefits you are bringing attending shows locally and what help you have given the local community - have you helped with fund raising for any charities such as the British Legion or Help for Heroes, for example.
I found my local council very helpful when I was having problems with planning permission with a neighbour about 10 years ago. Once the officials had found out that had helped the local museum with a WW2 display the previous year (and yes, they did check my story), they were sympathetic.
Good luck.