We are having this exact argument at the moment with our local council. There is a 3m planting strip behind our house, then a public footpath, then fields. We are trying to buy the land to extend our gardens, but a solicitor friend told us to check with the council regarding change of use. The council have said that planning permission would be needed to change from agricultural(as it is an ex field) to garden use, and that as the area is a planting area to provide a 'buffer' between the village and the countryside, we probably would not get permission.