If its just a static image and there is no zooming then thats maybe not that complex, unless there's some complexity I'm overlooking.
Using the scale of the map image you can convert that to points i.e. 1 point vertically is 10 miles. Then if you have your plot point co-ordinates you should be able to convert those to UIView x.y co-ordinate.
You could pick a reference point in the UK whose lat/long you know as an anchor from which to calculate the lat and long offsets from for the points you want plot.
Lets say there is a hypothetical tiny island in the top left hand of your picture, you can find out the lat/long for it and plot it at x,y of 0,0 when displaying your map image. Then you can calculate the difference in lat/long from that reference point of your pins and convert that difference into an x,y offset from 0,0.