Terrible
The young lead actress is from Birmingham, so she at least has an authentic accent.
I am from Birmingham, and have heard noone like that...
Spend a day in Dudley or Stourbridge, you might hear similar accents. I'm a Brummie & the dialect can be quite different to a Birmingham twang.
s'meant to be black country, not birmingham. tbh it sounds pretty good, to me.