Ubisoft has not made Assassin’s Creed Unity, Far Cry 4 or The Crew available for purchase on Steam in the UK.
UK customers can purchase any of the publisher’s catalogue for the holidays. That being Assassin’s Creed Unity, Far Cry 4 and The Crew, either through Uplay, or any other official key reseller like Green Man Gaming, GamersGate, etc…
You won’t find any of those games listed on the UK Steam page and Ubisoft has not explained why.
Speaking to PCGamesN, Ubisoft talked only about Assassin’s Creed Unity, “We’ve been in discussions with Valve about Assassin’s Creed Unity but for the time being the game is not available via Steam in the UK.
“In the meantime, UK customers wishing to purchase the game digitally can do so by visiting the Uplay store, our retail partners or other digital distributors.”
Keys purchased through other websites like GamersGate or Green Man Gaming will all be redeemable on Uplay as well. Ubisoft has set a £50 price tag for any of those games on UPlay.