Which famous English poet, at an early age announcing his admiration for D. H. Lawrence, excitedly wrote to his friend, “I have been reading Sons and Lovers and feel ready to die. If Lawrence had been killed after writing that book he’d still be England’s greatest novelist”?

The correct option is Philip Larkin.

Philip Larkin (1922–1985), who would go on to become one of the preeminent English poets of the 20th century, possessed a deep, youthful admiration for the works of D. H. Lawrence. As an undergraduate student at St John's College, Oxford, in the early 1940s, Larkin regularly corresponded with his school friend James Sutton, sharing his passionate reactions to literature and art.
In one of these letters written in 1941, the nineteen-year-old Larkin recorded his intense reaction to Lawrence's semi-autobiographical novel, writing: "I have been reading Sons and Lovers and feel ready to die. If Lawrence had been killed after writing that book he’d still be England’s greatest novelist."

This adoration for Lawrence's raw emotional canvas and vivid descriptions strongly influenced Larkin's own early creative output. His two published novels, Jill (1946) and A Girl in Winter (1947), reflect this early fascination before he established the more skeptical, melancholic, and colloquial poetic voice for which he is most famous.