Disc version or download version? If it’s the download version of the complete edition then you probably won’t have to install the expansion. I think it’s already installed after the main installation. As for the disc version installing every disc should be enough to get all dlcs and expansions.
If you mean the Game of the Year edition, all dlcs and expansions are already included.
It is the disc version and says complete version across the top of the case. Bought it at game stop I have installed it and played about an hour into the story and the expansion hasn’t become available yet didn’t know if I was doing something wrong
The expansions won't trigger while you're in the starting area (White Orchard). If you haven't left that area yet, then I wouldn't worry.
(You should have the option to start a new game from either Hearts of Stone or Blood & Wine in the main menu, but that's not ideal at all when playing the game for the first time. You can check if the options are available to make sure the expansions are working properly, though.)
The game incorporates both HoS and B&W into the overall campaign. You'll eventually come across their storylines as you play. I'd strongly recommend playing through everything this way, at least the first time you experience the story.