Welcome to the forums Zaio!

From this, it sounds like you have the original. I suggest buying the Vikings Invasion expansion pack, which add new factions, new units and a new campaign.

With the VI expansion pack, you can add some super mods like the XL Mod or BKB's Super Mod 2.0, which are available for download in the Engineers Guild section of this forum(the big forum, not the Entrance Hall)

Also, you can wait till the end of this year, when CA is going to release Medieval TW II.

Hope it helps!!