Carla's accent in 'Jurying'

As an american fan of Peep Show, I sort of group the accents that I can understand into a generic 'british' accent category. I know there are quite a lot of accents in the UK, but I'm not familiar with all of them.

When I watched 'Jurying' the other day, I had trouble trying to understand where Carla's accent is from. What is her accent called? Where is she from? I can't remember if they said in the episode. Also, I thought Toni sounded american? When she's at Super Hans' flat in series one, she didn't sound like she had an accent when she opened the door, to me at least.