Specimens of Erica in Bloom

Can any of your correspondents oblige me by the information where I can procure specimens in bloom of the following plants, viz. Erica crescenta, Erica paperina, E. purpurea, E. flammea, and at what season they come into blossom in England? If specimens are not procurable without much expense and trouble, can you supply me with the name of a work in which these plants are figured?