While I do agree the reporting in Italy is likely to be a bit more reliable than the reporting from China (and more indicative of the trends that can be expected in the UK), I don’t think there is any evidence for that high of a mortality rate just yet.
As it is, the estimated mortality rate ranges are concerning enough, anyway.
And, unfortunately, with the virus’ estimated R0, short of an authoritarian lockdown like China implemented (which is never going to happen with us), exponential growth was always on the cards.
Now all we can do is properly prepare, practice good hygiene, lookout for each other’s wellbeing, follow reputable guidance, and keep laughing.
My motto has always been: prepare for the worst, hope for the best, and expect something in between.