I would like to plot a map of the coastline of the British Isles using gnuplot, for which I need a data set of points along the coast. Is this available in csv form, please, or help to convert it to this format? A low resolution outline is all I need.
The European Environment Agency hosts shape files of European countries.
The British Isles: http://www.eea.europa.eu/data-and-maps/data/eea-reference-grids-2/gis-files/great-britain-shapefile
This online tool converts
.shp files to
.csv: https://mygeodata.cloud/converter/shp-to-csv (I haven't tried it)
Check OpenStreetMaps Overpass API, which is geared at data consumers.
The outline of British Isles is definitely available in OSM. It boils down to how to extract it from the database.
After some googling I found this page, which lets you download borders from OSM. Maybe this is what you're looking for.