Complex sentence: Few hill forts have been substantially excavated in the modern era, Danebury being a notable exception but it appears that they were used for domestic purposes with examples of food storage, industry and occupation being found within their earthworks.
Split into simpler sentences: Few hill forts have been substantially excavated in the modern era, Danebury being a notable exception. However, it appears that they were used for domestic purposes with examples of food storage, industry and occupation being found within their earthworks.