I watched two episodes and then I was done. Stupid beyond belief.
Remember that the ancient Saxons (who would have most likely would have arrived via Denmark) were part of the British establishment by the 870 a.d. era depicted in the movie.
The Vikings raided Russia (or more precisely, the Baltic States) first not because they didn't know about the British Isles but because it represented a closer and softer target.
I gave up on the series after the first episode.