In reply to Jan Hofheiz:
I've just logged back in to the OS website to print maps for tomorrow.
They've changed the 'Print' tool lay out, taken away the preview page(which wasn't a true reflection of the area you were printing) and have instead got the print area highlighted on the main map.
They've also changed the 'select to fit' options. Kept the print map scale and got rid of the 'fit to page' option.
I always chose the 'print map scale' option and never had a problem with the scale of my print outs.
This evening however it's all over the place on a 1:25k map print the scale for grid square is between 800m (no other personal printer options selected) to 950m (no margins and 100% scale).
I'm a bit hacked off as there was no issue for me a month ago and i subscribe to OS because i can print the maps whenever i want.