The Walk Manager used to load new walks onto the system, provides a number of ways of identifying the start point.
You can provide a grid reference, or just manipulate a map to find the location.
The walk manager then provides the Grid Reference, Post Code and W£W Reference.

There is a function on here that lets you find such information by simply right clicking on a map.
This is available at two locations on the site, namely:-

https://lancashire-ramblers.org.uk/self-guide-walks/plot-a-route.html

OR  https://lancashire-ramblers.org.uk/walk-leading/aids-for-leaders/plot-gpx-s.html

These both open up a map.
The icon at top right of the map will let you choose different map formats. (Bing, OS...)

Use the search functions or move the map about to find the start of your walk.
Zoom in fairly close.

Now RIGHT CLICK at the start point.
A box will appear giving various reference values for that point.
e.g. Lat/Lon,  UK Grid (6 & 8 Digits), Mapcode.

It previously also showed nearby Post Codes which was useful for detemining the best one to include.
Just at the moment that appears not to be functioning.
After a moment, a number of "envelopes" will appear showing the nearest post codes.

Click on the post code of interest and it will show the post code and distance from the point.