Perhaps someone (currently or more recently serving) will be by to confirm or clarify.
DDC (or Safe Driving Course as it is now called) is not a course that will teach you to operate a motor vehicle, nor will it be a qualification that allows you to take a road test to get 404s (or at least it didn't in the old days). To operate military pattern vehicles you would need to do a Driver Wheeled course. As already explained, DDC is available online, in the old days when I first did it in the military (far too rapidly approaching a half century ago) it was the better part of one day in a classroom. And looking through my collection of useless certificates, apparently I did it twice (successfully since I got the certificates) before I did it again as part of the Driver Wheeled course, all in the space of a few months.
And DDC is not a unique military course. It is a civilian course adopted (and adapted) by DND. The programme that used to be given by DND was the one from Canada Safety Council
. There are a number of organizations (non-profit and for-profit) that provide the training, both on-line and in-classroom. I don't know about BC, but in Alberta completion of a DDC course counts toward reducing demerit points on your license.