I was just doing some basic maths by looking at age demographics and the current death percentages.
There are 3,281,955 people aged 80+ in the UK. If you go by the 70% infected rate, that means 2,297,369 will be infected. With a 14.8% death rate you get a figure of 340,011 dead. That's just the 80+ age group, even if you half the mortality rate you still get 170,005 dead. This is avoiding the scenario where the sheer scale of people requiring hospital treatment results in higher fatalities.
I stopped doing the maths once I reached my Mums age demographic because it felt a bit terrifying frankly. I didn't even bother checking Italys current age to death ratio, I used the current UK one but given the nations strategy is to say "feck it" then we should be looking at worst case scenario figures right now.