Hi there, nice to meet you
We use K12, and I supplement a great deal (the k12 is their base). We originally went with k12 to start with because it was free and and all in one. At that time piece parting and entire curriculum-at no cost-was beyond daunting to me. I didn't have the resources to just buy what we needed, even at deep discounts, it wasn't happening, lol. We did our first year(which was really only half a year or so) on just that k12 curriculum. Last year I did both, used K12 as a base(again because it's an all in one) and I supplement-a lot. Some people think it's weird to use a base at all, but it gives me good jumping off points. It has other pros as well. The few cons it has I can overcome by supplementing, so it works out really well for us. Many think anyone who uses any kind of online schooling, or umbrella school isn't actually homeschooling. I would love for them to spend a week here in this house, they'll change their minds
We are also secular-probably more than most who say they are, lol. It can be difficult to find purely secular things, and others have already given the links I would have offered, lol. It is entirely possible to find what you need or to supplement/switch up a subject if there is something you're very interested in but it has a more religion based tone to it. You can always use that as a jumping off point rather than an actual lesson. If that makes any sense. I hope it does, it does in my head, haha.
At any rate, welcome

The ladies here are fantastic and there is a crap load of great advice and resources to be found here. You've come to the right place. I recommend checking out the links and stuff up in the resources sticky and the other sections too. There's some pretty interesting stuff in there.