QCT files are easy to make - if you have the right version of Memory Map. You need to download the free MM desktop software & then buy the US$50 Discoverer to Navigator upgrade. The OS made MM remove all mention of it from the UK website but the US website has
details.
If you don't want to scan & calibrate your own maps, the trial version of
MAPC2MAPC will convert an Ozi calibration file into a format acceptable to MM. You can convert any Ozi desktop map into a qct map in a couple of minutes.