Complex sentence: He spent the holidays as a tutor in the western Highlands and his poems "Glenara" and the "Ballad of Lord Ullin's Daughter" were written during this time while visiting the Isle of Mull.
Split into simpler sentences: He spent the holidays as a tutor in the western Highlands. His poems "Glenara" and the "Ballad of Lord Ullin's Daughter" were written during this time while visiting the Isle of Mull.