no, british ginger beer is way hotter than root beer.
It's mellower and sweeter than coca-cola. It has a sassafras taste to it that would be hard to describe to someone who hasn't had sassafras. It mixes well with vanilla and that's what makes root beer floats (vanilla ice cream plus root beer) work so well.
I'm guessing root beer barrels (the candy) aren't available there? I've had a ton of British and continental candy and I can't really think of anything similar.
If you're in the states and want to try horehound, go to any Cracker Barrel restaurant (I don't know how it is elsewhere, but they're like every freeway exit in this area). They have a shitload of the stuff. You can get horehound stick candy for 10 cents apiece, or they have little papery sacks of it for around $1.50.