The shipping forecast is also easily received all around the UK and offshore from the UK coast, it's transmitted on VHF radio. Getting up to date gribs requires an internet connection, mobile signal is pretty decent up to a few miles offshore I find but half way across the channel or the north sea you've got VHF only (or expensive satellite internet) so the shipping forecast on the VHF on passage lets you know if the weather remains as expected or if there's been a sudden change and you need to change your plans or prepare for some heavy weather.
Edit: I should also say the shipping forecast/inshores forecast is available in a minimal text-only form on the met office website, often I'll just read the text (handy for patchy or expensive internet connections) it is fairly rare for me to actually listen to it on the radio.
It gives an awful lot of info that's simply not in general forecasts and apps. Specialised apps can go the other way and give way too much. You mention flying, back when I used to fly a little I found it's a heck of a lot more friendly than decoding METARs, so it's a good starting point if thinking of flying next day. The main thing missing is cloudbase - that's easy, poke your head out the door. :)
I hear of people listening to the Shipping Forecast and falling asleep, only to be woken up again by the National Anthem.