I think we are a bit backward in the UK when it comes to peppers/chilli's. ("chilli" or "chili"?) Labelling in supermarkets seldom extends beyond "pepper", "sweet pepper", "mixed chilli's". At the market I can get Scotch bonnets, birds eyes and jalapeños, but that's about it. I do have some dried anchos, but I've no idea why.
I agree regarding supermarkets. In fact its only quite recently that jalapenos appeared I think. But I was looking at the Devon Chilli Farm - one of the UK's foremost chilli growers. No sign of poblanos but plenty of other types.