Since yesterday i have tried another printer, a Canon iP7250 A4 and at least i managed to print from this though i was unable to change the orientation of either document or feed to printer so it came out partly printed across part of the envelope.
As a workaround i thought about redesigning the document in vertical layout then rotating text boxes and trying to place them in sideways orientation was just so inaccurate.
I also thought that exporting to a JPEG format and rotating this might work but the saved JPEG just didn't line up with the envelope and was useless.
Does anyone know a way of rotating an original document created in Affinity through 90 degrees clockwise? At least I could then try printing of the Canon A4 even if I still don't seem to be able to do it on the Canon 9500?