Complex sentence: He has lived there since the age of fifteen months, having previously lived with his parents in Godric's Hollow; however, since he began attending Hogwarts, he spends little time there, though he reluctantly returns during the summer holidays.
Split into simpler sentences: He has lived there since the age of fifteen months, having previously lived with his parents in Godric's Hollow. However, since he began attending Hogwarts, he spends little time there, though he reluctantly returns during the summer holidays.