Councils are more sympathetic to granting people permission for live/work units. However, any new dwelling on greenbelt will contradict policy. There are only a few exceptions to this – converting an existing building, replacing an existing dwelling, or building a new dwelling to serve the agricultural business.
I’m afraid that success in cases such as this is rare. On occasion people have put up things like stables and then a few years later successfully applied to convert it. But I would not recommend this as there is no guarantee that you will be granted permission for conversion.