Well yes, of course british, irish or scottish. It's supossed to be in Europe.
I still believe the LoS series doesn't take place in Romania, but some undisclosed nation in an alternate fantasy version of Europe. And by all means, it doesn't have to take place in Romania. If they were given enough leeway to do their own thing, it COULD be set in any country they choose, even the British Isles. It doesn't follow actualy history, it doesn't follow Bram Stoker's novel, and doesn't even follow the original canon. I think it has enough room to establish itself anyway it wants. As long as it doesn't go the Blade Trinity route, saying Dracula was an ancient Roman warrior, we're fine.
Though, what you said did make me laugh, as I recalled watching the "Everything Wrong With" CinameSin video for "Les Misérables", and recalled the guy pointing out that it's odd that a despite being set in France, everybody speaks with an English accent(even the American actors). That also made me think of movies like Troy, Clash of the Titans(remake) and Gladiator, where the majority speak with English accents, even the scattered American actors convert to speaking in English accents(and some are pretty bad).