head outvi phrasalphrasal verb, intransitive: Verb with adverb(s) or preposition(s), having special meaning and not taking direct object--for example, "make up" [=reconcile]: "After they fought, they made up."
(leave, start a journey)
启程 qǐ chéng
出发 chū fā
Henry was getting impatient to head out on his own.