In the rest of the UK, it's a little more complicated (for now): https://en.wikipedia.org/wiki/Freedom_to_roam#England_and_Wa...
We have an extensive network of public foot paths and bridal ways that private land owners aren’t allowed to block if they go across their land. There are several through sheep fields, cow fields, crop fields and even a couple of stable fields where people keep their horses with a 5 minute walk of my house.
I can't believe this actually needs to be said.
Not really :)
However I had just read this: https://www.bbc.co.uk/news/world-us-canada-68077595
There's a fight going on around "corner cutting" - https://earthjustice.org/experts/tom-delehanty/wyoming-court...
The end result is that you can essentially 'point in a rough direction' and walk however far you want, however not just on any part of the land. A good OS map, analog or digital, helps.