You may find the sites below interesting or useful:

Ron Scamp's Quality Daffodils for a full range of Cornwall-grown daffodils, many of his own breeding. 

The Daffodil Society is the specialist society of Great Britain for all who are interested in the Genus Narcissus, by way of exhibiting, breeding or just lovers of the true heralds of spring. The Society objectives are to advance the education of the general public into awareness of the whole of the genus narcissus.

The Cornwall Garden Society holds an annual Spring Flower Show at Boconnoc as well as organising a series of events during the year. In spite of it's name, the CGS is open to residents of Devon.