Sand and dust will stick to any grease - whether it's copper, lithium, chip fat, sun block or anything. Probably best to stick to lubing yourself with the last one (or getting someone to do it for you
For the car why don't you just stick to what the manufacturer recommends. You'll probably find loads of the stuff in Halfords, it's cheap enough and there can't be that many greasing points on cars built in the last 20yrs.
I normally just use copper grease for static nuts and bolts that are subject to heat (eg exhaust brackets, brake calipers etc ) that I want to be able to get apart again. If the parts move relative to each other in normal use ( stuff like bearings) I tend to use something else as I've heard that the copper part of the grease can act as a kind of mild grinding paste. Whether that's true of not I've no idea but better safe than sorry and I've plenty of other cans in the garage.