One way to get For Honor cheaper is to use 100 Uplay points for a 20% discount = £31.99. I did this last night, though the extra points got me the Deluxe edition.
The other way is to use Gamesplanet which seems to be the cheapest for the standard edition at this moment in time.
Credit to zHamzz and Moonky for highlighting this deal. Really looking forward to playing this later. I gave into the hype and purchased.