Yeah I agree with J.R's answer, QGIS is certainly an option and I might even go that route since I'm already familiar with it, but for someone who hasn't use it much I'd probably suggest something like Visio or another program that's more based on drawing than on displaying georeferenced data.
However, if you're map is going to be very complex and you want ...
GIS software (including QGIS) are good for making city map but that mostly true for ''real'' city map because you can grab some existing data and ''just'' display those data the way that please you (choosing color, fill, line thickness, etc.) and label the thing you want labeled easily.
For fictional map you don't have existing data so using GIS for ...
Looking at the Inverness node suggests that it isn't in GB (it isn't really an admin unit).
is_in Highland;Scotland;United Kingdom;Europe
is_in:province United Kingdom
So I would try something like:
The Mapzen Borders project would have provided exactly the data your looking for, but Mapzen is dead, and the download links on that page all 404 now.
What the Mapzen Borders data was:
Each country link contains a zipped directory of geojson files, each describing increasingly detailed administrative boundaries. The hierarchy varies by country but in the ...
Contradicting my own comment, here are a few suggestions (not recommendations) I found by some quick searches. I tried the websites but not the apps.
GPS Visualizer: website that lets you draw points and lines (but not polygons) on a map and export it as a gpx
http://geojson.io/ : website that lets you draw points, lines and polygons and export ...
The Discover the action around you with the updated Google Maps blog post may be of interest. The brownish colour refers to Area of Interest, which as they describe:
We determine “areas of interest” with an algorithmic process that allows us to highlight the areas with the highest concentration of restaurants, bars and shops. In high-density areas like ...