[This answer explains the importance and value of maps and compasses][1]. An additional point worth making is that many popular trails will have periodic signs giving location information such as nearest street, postcodes, and, best of all, [Ordnance survey grid-references][2].

Here is an example where the grid-reference is ST835128]:
[![enter image description here][3]][3]
(the 'ST' part is not on the sign)). The point of those signs is to enable you to give concise location data in the event of requiring emergency services. So, as you walk along, look out for these signs and either take note of or memorise some of these data (until you get to the next sign).


  [1]: https://travel.stackexchange.com/a/144263
  [2]: https://getoutside.ordnancesurvey.co.uk/guides/beginners-guide-to-grid-references/
  [3]: https://i.sstatic.net/wEf1D.jpg