I’ve been hunting for a radar app as good as Dark Sky ever since it was discontinued, but not found one so far. Currently I’m using Ventusky (on Apple) because it provides a lot more detail than rain radar (wind gusts, air pressure etc).
It's great. Has overlays for wind, radar precipitation, satellite cloud cover, you name it. Plus you can compare the forecasts from a lot of the big name forecasting models.
It shows cloud cover as well as rainfall, and also has a few other views I don’t use. But what I really like is the iOS home screen widget, which shows me my local weather even when I’m not actively looking at it.
It'll be interesting to find out. I personally use rainviewer app on Android for rain notifications/radar. It's been hit miss so far, but generally the same as metoffice (but it has rain radar widget which is what I like)
The above link and rainviewer both have the same rain cloud heading in my general location. The linked app says there will be rain in 25 minutes but no one else does.