There is a new book by Sandy Byrne titled The Poetry of Ted Hughes: A reader’s guide to essential criticism (Palgrave Macmillan, 2014) attempting an overview of "essential" criticism of Ted Hughes's work. More details here. A review by Ann Skea here.
New book reviewing contemporary Hughes criticism by Sandy Byrne
Sandy Byrne: <em>The Poetry of Ted Hughes: A reader’s guide to essential criticism</em>, Palgrave Macmillan, 2014