Mechromancers

So i've been playing on Tunggle for a while now, and i cant seem to join most servers even with 250 players, so i updated my 1.0.0 to 1.4.0 w/ dlcs (Sir Hammerlocks Big Game Hunt, Capt. Scarlet Dlc forgot the name, Tourge's Campaign of Carnage and Ultimate Vault Hunter Update 1.4.0.) Now Problem. I want to play as Mechromancer (yeah i've heard bad reviews of it, but i wanna try it out) is it in one of the patches i missed or is it like a dlc too?

Its a separate DLC for Borderlands 2.

Steam store? or some Cdkey websites