First Creeping Charlie: Creeping Charlie loves shade, so if it's possible to do any pruning that increases sunlight, that will help (though it won't kill out any that is already established, I don't think). If you find small amounts invading an areas, pull it by hand, ASAP. The long runners usually pull up pretty easily. For larger areas that are really overrun with the stuff, there isn't really much you can do to remove it, aside from using chemicals. There are two options: One is conventional broadleaf weed herbicides. This is a tough weed, and usually requires two applications, one a couple of weeks after the first. That usually does the trick. When herbicides fail, which happens a lot, it's usually because people don't do the follow-up treatment. The other option is the much-discussed 20 Mule Team borax treatment. The recipe (this is from the University of Minnesota Extension website, FYI) is: Dissolve ten ounces of Twenty Mule Team Borax into four ounces of warm water, then dilute it in 2 1/2 gallons of water. This should be sprayed evenly over 1,000 square feet of lawn, no more, no less. The most you should treat your lawn with borax is once each spring for two years. The problem with borax is this: Even a slight overdose can make your soil toxic to plants for years. It doesn't break down the way most herbicides do. So even though it's often recommended as a natural substitute for synthetic herbicides, it carries substantial risk. You stated you were in Canada, and so you're probably limited in what you're allowed to use. So hopefully there's something here that will be of use to you. This is pretty much all the options you've got, save killing the entire lawn and replanting, which is not a very good alternative.
Now Moss: Moss thrives in moist or shady conditions (typically both). The problem is, those are exactly the conditions that lawns DON'T like, so the problem is really two-fold. The moss is invading an area, in part, because the grass is struggling to survive, leaving thin, open areas where the moss can gain a foothold. In sunny, drier areas, by contrast, the conditions are tilted in grass's favor, and moss will not generally be a problem. If there's any way to increase sunlight and decrease moisture, do so. Can you improve drainage? Can you prune up some low hanging branches? Those steps may help. Also, raise your mowing height, and be sure you overseed the area with a shade-lawn mix, if you haven't already. If you can't do these things -- or if you have and it didn't cure the problem -- then you might consider turning the problem area into a bed for shade-loving perennials instead. It's true that you can kill moss. Scotts, among others, carries a moss killer, and it works okay. But it doesn't cure the underlying issues, and The moss will eventually return, requiring repeat treatments. Rather than fight it, it's better to cure the underlying issues, or just stop trying to grow a lawn where it's not suited. Final note: You'll often hear that moss prefers acidic conditions, and therefore you should apply lime to raise the pH. That won't hurt, but my opinion is that this isn't usually the primary problem. It's generally a combination of shade and moisture (although moss will thrive in sun too, if given constant moisture and a thin lawn).