I'm from the Uk and want to purchase all the official add-ons, but the Bethesda store states it does not deal outside North America.
I already have a copy of the game so I have no intention to use Steam- where exactly am I supposed to get this...?

You can get them https://orders.gamesas.com/dlc/ Knights of the Nine is the only one available in a language other than english, but all are available.