Complex sentence: Farmer had no formal teacher training when he went to be Head of Music at Ashmole School in 1972 and two years later to Holland Park School, London, where he developed the use of pop music in music teaching.
Split into simpler sentences: Farmer had no formal teacher training when he went to be Head of Music at Ashmole School in 1972. Two years later he went to Holland Park School, London, where he developed the use of pop music in music teaching.