We are after a digital high resolution, colour background to make a large planisphere (probably 1m in diameter) for 52 degrees north, showing the Milky Way and some Messier objects.
Does anyone know where we can find one or make one?
Would be worth talking to @DominicFord – he has a generator at in-the-sky and it was used for generating a big planisphere in an Australian dark-sky park. You might be able to annotate the generated map, or Dominic might be able to help you.
You should be able to load the SVG or PDF files into any good vector graphics package (e.g. Adobe Illustrator or Inkscape) and print them at arbitrarily large sizes.