Complex sentence: He travelled widely in France and Italy as a freelance photographer building up a portfolio of photographs, before going back to work at the Courtauld Institute for twelve years, travelling extensively around Europe to photograph historic architecture and sculpture for the Conway Library at the Courtauld.
Split into simpler sentences: He travelled widely in France and Italy as a freelance photographer building up a portfolio of photographs. He went back to work at the Courtauld Institute for twelve years, travelling extensively around Europe to photograph historic architecture and sculpture for the Conway Library at the Courtauld.