There are two expansions, Ringed City and Ashes of Ariandel.
How many DLC areas are there? I completed the base game but not the DLC, if there is only one I might not bother
Be warned, the Ringed City dlc is not for the faint hearted. The first boss has given me tourettes.
Hopefully Microsoft will match this, I missed it last time they put it on sale!
Note that you have to be a certain level in the main game before you can access the season pass content