I'm pretty sure if the add-ons are on the same system you intend to play the game on the it should be fine. Assuming you mean the Elder Scrolls DLCs? If not then I'm not sure what add-ons you mean.
By Ambrosia Midkiff on January 7, 2016
You may only NEED internet if you have to update the game on your system, otherwise an internet connection is not required to play the game seeing that there is no mmultiplayer.
By Andreus Young on March 6, 2015