Complex sentence: His parents separated when he was young, as a schoolboy he contracted polio, and, for the entire six months that he was in Liverpool Royal Infirmary, his only family visits were from his sister Susan.
Split into simpler sentences: His parents separated when he was young and as a schoolboy he contracted polio. For the entire six months that he was in Liverpool Royal Infirmary recuperating, his only family visits were from his sister Susan.