The idea of playing as Batgirl in Batman: Arkham Knight is a super exciting prospect. I really like the character and being given full reign to beat up bad guys as her in the context of the Arkham Knight is exciting. The DLC paywall she is behind is less so, but hey.
Well, the DLC called A Matter of Family has finally been dated and will be available to Season Pass holders on July 14th. Don't worry if you don't want to go all in on the Season Pass though. The DLC will be available on July 21st for £5.79 on its own.
Now the question becomes length. I heard the Harley Quinn DLC has very short, and that price range doesn't give me huge confidence it will be a lengthy jaunt, but we will see. If there is an hour of play in there, that is probably just about on the side of reasonable.