Complex sentence: At the age of eighteen she ran away with the actor Robert Baddeley, then acting at Drury Lane, and she herself made her first appearance on the stage there on the 27th of April 1765, as Ophelia in Hamlet.
Split into simpler sentences: At the age of eighteen she eloped with the actor Robert Baddeley, then on the stage at Drury Lane. She made her first appearance as an actress there on the April 27,1765, as Ophelia in Hamlet.