Hello and Welcome @DragonRoaria
It’s a great idea to get advice and we are happy to help.
First make sure you read this:
No submission is a gimmie 
it is up to the submitter to make the case for each submission. Put in the effort and you are more likely to have success.
Don’t worry about things like who owns the forest etc in the U.K. you are ok.
It doesn’t matter that the signs are simple you are nominating the trail/ route. It is the route that is interesting not the marker. So present an interesting route.
The NCN 47 marker should do well.
Make sure the title is specific for example NCN47 marker Holly Lane
Have the description say something about NCN 47 length, start- finish, and something specific about this section - what will people see a nice walk across fields between villages, nice view that sort of thing.
In the supporting info you can add a link to the sustrans webpage for 47. If it is visible on streetview say so, if it’s not explain how someone can verify the location from what they can see. The supporting photo needs to show the actual sign with enough of the surrounding area to help with that task of verifying.
The PROW can be trickier
This is a great resource you can use it to check the official number of the route. Every PROW has a distinct set route clicking on it on the map will bring up the details Use this information. I put the official numbers in the supporting information.
Then take the same approach as outlined for the NCN 47, for title description supporting. Your example is good as it is clearly at a decision point for which way to go in order to follow the route so a good anchor point.
A PROW that is a short passage between houses is not likely to meet the criteria of explore but one that takes you on a longer interesting route can fulfill that criteria.
Sorry this is so long there is a lot to absorb. But if you get it right it becomes easier.
Please feel free to ask more.