These things are obviously very subjective, and I understand Britain was bombed a lot during the war, and very poor after it; but even compared to poorer cities across Europe, ours just don't match up, particularly to those in Italy (although tbf everywhere is ugly compared to Italy), Spain, France, etc.
I know I'm making a big generalisation, and there are obviously notable examples to the contrary (Edinburgh, Bath, York, large parts of west/central London, etc.) but I just get the feeling that, in an effort to 'modernise' and build a lot of affordable housing very quickly (which was very commendable thing to do, for the record), along the way we made some bad design decisions.
In the postwar era, virtually all of Europe ended up with a housing shortage as the baby-boomers started moving out. And thus most of Europe ended up building large housing projects, in concrete, often using prefab elements, in what was the dominant style of urban planning at the time.
Britain and it's (in)famous concil estates are far from unique at that. East Europe had its infamously dreary concrete districts and 'Khruschovkas'. France's banlieus, Gemany's Großwohnsiedlung, the Miljonprogram areas of Sweden, and Italy was no exception - behold the Scampia area of Naples. Palermo in Sicily is a partciularily bad example in fact, suffering from a combination of wartime damage, poverty and years of deeply ingrained corruption. In the postwar era, whole neighborhoods were erected there, much as elsewhere, and with government support much as elsewhere, but with insufficient roads, schools, parks etc since corruption had been allowed to do an end-run around city planning regulations and such.
So anyway, what you're describing does not seem to be unique at all to the UK, and nor is Italy except from the phenomenon. So you'd need some kind of actual quantitative comparision to justify the assumption that the UK is worst. For all I know it might be, but it's not easily measured.
