Thanks to Stuart G7KBF who has found 2 really useful websites for radio amateurs:

Looking for a source of great circle maps I came across this website where you can create your own.  The website created by Tom NS6T can be found at 

https://ns6t.net/azimuth/azimuth.html

The great circle map on the website is referred to as a Azimuthal map and with minimal input creates a great circle map based on your QTH's locator square with a radius of your choosing. (The square is also known as a Maidenhead grid square).

Don’t know your locator square?  This can found on another website at

http://qthlocator.free.fr/

Opening the website it locates on Paris but come out until the UK and East Anglia are obvious home in on Norwich until the map shows the building/street you are interested in click and the information gives your locator square.   You may have to come out so see the blue square which shows the area of the locator square. As an example the QTH locator square for Norwich Castle is JO02PP.  (latitude and longitude are also given)

After finding your locator square place this in the location box of the Azimuthal map create website.  The distance box, if left empty, gives you the whole world but for more specific interest inserting 3000 gives you a map that reaches Greenland, Turkey and North Africa with your QTH in the centre.

The inserted figure equates to the radius in km from your QTH locator.  For VHF a smaller distance is suggested, sporadic E and HF (by Band?) it is up to you to experiment.  Unlike a “flat map” a great circle map gives true direction and distance.

As an addition comment the GTH locator can be used to measure the distance between two squares.

Stuart G7KBF