HELLO!!!!!

I've been using NMM exclusively up until now, just so things are simpler, but, if I was to download a Workshop only mod, would I have to activate that through the Skyrim Launcher, or is it possible to do this via NMM?

I believe you would have to open the launcher to download and install SW mods, since it is the manager for that system. However, once installed NMM could be used to set the mod's load order, and whether or not it is active.