Complex sentence: He was inspired by the trumpeters Louis Armstrong and Nat Gonella, he taught himself the instrument and formed a quartet at the school in 1936 which also included the future journalist Ludovic Kennedy on drums.
Split into simpler sentences: He was inspired by the trumpeters Louis Armstrong and Nat Gonella. He taught himself the instrument, and formed a quartet at the school in 1936 that included the future journalist Ludovic Kennedy on drums.