If Game of Thrones is House Targaryen, then The Last Kingdom represents the Blackfyre Pretenders, as it's clearly targeted to cash-in on the success of HBO's show and be the 'new Thrones'.
And yet there is something worthy in the comparison. The show doesn't feature any magic - which is a plus for any viewers not so keen on that element of Thrones - and it's full of family drama and political tensions, along with some big action sequences. It's even set in an England divided into seven kingdoms, which face invasion from the Danish.
It's based on a series of novels too - from Bernard Cromwell - and Season 3 is expected to air late-2018, so there's even plenty time to get caught up before that arrives (Seasons 1 & 2 are available on Netflix in the U.S.). If you're after the closest thing to a direct copy, this is one of the strongest bets.