The design of your house will greatly depend on the locality, location, situation and size of your plot. It will also be heavily influenced by the opinions of the local planning department. The key to success is hard work. If you can, get to know local people, get a large-scale map of the area, walk the footpaths or at the very, least drive around. One of the most likely opportunities might be provided by an existing dwelling that was badly built within the last hundred years and which is now in a poor state of repair and ready for replacement.
Planning permission is very likely to cause problems in one way or another.
Don't expect to get planning permission on a green field site just because you intend to rebuild the most attractive barn in the county. Your plot will almost always have to have a sound planning reason for permission to be granted. For example, if you are replacing an existing dilapidated dwelling, or there is already a listed barn on the site which will be lost if it is not given a change of use, or you are infilling within the village envelope, etc. If you are to convert an existing barn, expect the local conservation officer to have some very strong ideas about keeping windows to a minimum and the internal areas open and spacious. The generally accepted deal is that you are allowed to convert the barn to a dwelling on condition that you retain the characteristics of the barn.