The British Library has been blogging about their recent Ted Hughes archive acquisition all year. Helen Broderick is the lucky archivist processing the collection, and she posts pretty regularly about her progress, findings, etc. Plath is mentioned in two posts.
The posts are adorned with images throughout that are wonderful to see. As an archivist/librarian myself, I am envious of Ms. Broderick's experience and thankful to her and the British Library for this kind of attention.