Hello 😉
Margins: There are two margins. One is completely white and is about 12mm on every side. The other is a faded area which shows the grid square numbers (and OS Copyright info) and is around 10mm all around. If I’m that fussy about the latter, I just make sure there is some overlap. Switching off the latter might be handy but there doesn’t seem to be an option for it.
Print Quality: Stunning on my Epson Inkjet. I always opt to use the print using system dialogue option rather than the default settings as I can then adjust for paper type etc. Make sure you have any Photo Enhance mode switched Off.
FWIW, the new version of Getamap should be with us in a couple of months.