Hi witsonpeter. Welcome to the forums.
Color on a screen is quite different from printed color—indeed, almost the opposite. Combine all screen colors (RGB—red, green, blue) and you get white. Combine the primary print colors (CMYK—cyan, magenta, yellow and black) and you get black.
To get an accurate idea of what colors you will get in print, it's useful to get your hands on a "4 color process guide", which is a booklet of strip cards giving the printed color for each digital color value. (It's like the color cards you see at a paint shop when choosing paint colors.)
Without this, it's quite hard to get an accurate idea of what colors you will get at the print shop. But each shop also has its own inks, so it might be worth speaking with the printers first to see if they have a color guide of their own.