Complex sentence: He began his medical education as apprentice to his father, and continued it at Guy's and St. Thomas's hospitals in London for three years, after which he settled in practice as an apothecary at Highgate, and there remained for ten years.
Split into simpler sentences: He began his medical education as apprentice to his father, and continued it at Guy's Hospital and St. Thomas's Hospital in London for three years. He then settled in practice as an apothecary at Highgate, and there remained for ten years.