This is a very topical pun in the UK at the moment following the public choosing the winning name for a ship in a public vote as Boaty McBoatface. Your term is a variation on that, possibly to do with the upcoming EU referendum but more context would be needed to know for sure.

It refer to a current joke from an internet poll where internet users could choose the name a ship. The most popular name was the very silly "Boaty McBoatface" (you can look it up). Your phrase is a variation on that joke.

More context is needed, but it probably means someone who constantly talks about voting. In english it's somewhat common, at least in America, if someone talks about something to say ____ Mc_____face, like Pizza McPizzaface, or Richey McRichface. It's meant to make fun of people.