There are giveaways that the 'Manchester' scenes were not shot in the UK. For instance British urban streets to not have a mass crossing wires (it's all underground) and the road signs are subtly wrong and the street lighting is American.
In the third episode, while 2 characters are shown under the covers implying sexual intercourse, the male character's boxers are visible.
The scenes supposedly set in Manchester were clearly filmed at least 3000 miles away from the UK. British terraced houses do not look like that from the outside, and in the UK they use three pin plugs for electrical appliances.