The biggest aircraft in the world the AN225 which was built to carry the Russian space shuttle should be crossing the coast just west of Worthing in about an hour
Put the flight number ADB3473 in search on Flightradar24
It’s not censored or monitored if military aircraft don’t want to be seen they have their ways and means it’s just showing ADS B in peacetime civil authorities ie ATC need to know where military aircraft are and visa versa, it’s just Flightradar24 chooses not to show military, having said that...
Click on the more info button at the bottom, then scroll down to the first info block and there you can see what routes the aircraft has flown ( free ) for the last 7 days.
You will be amazed to see how many sectors Ryan air/ Easy jet do.....then look at the distances large aircraft fly in 7...
On FreedarUK
Military are shown Green
Air Ambulances RED
Biz Jets Black.
Commercial White.
Same as the other apps aircraft sizes ( defined by wake turbulence ie Heavy/medium.) are depicted by the shapes...as are gliders.
If you want to see all military aircraft as well then FREEDAR.UK is the one to use.
Not as smooth as Flight radar 24 but then that dont show the majority of military.
https://www.freedar.uk/
The app is available in the App store
Also try plane finder from the app store