I live in a Tier 3 city in a HMO. Self-contained room, just a shared kitchen.
3 other rooms here, but I virtually never see them,apart from occasionally passing in the hallway.
Don't mix with them so essentially socially distanced from them at all times. Don't even know most of their names !
I don't view it in the same way as if I were living with friends, family or a partner. On this basis, do you think I can bubble up with my partner who is in tier 1?