Welcome Monica!
I also live in a place with venomous critters and I hear you. I live in a place with different bugs and did some research to see what might help and it seems it's the same as the centipedes we have here (Brazil).
https://www.krqe.com/news/new-mexico/centipedes-in-new-mexico-what-attracts-them-to-ones-home/
I thought it was interesting that they're attracted to humid spots. I always find them in the front near my dog's water bucket, so I suppose that explains that. So they're probably looking for water or for food (other bugs). keeping those things off the catio (or removing places where water might condense after temp changes) might be useful.
Something we do to keep brown spiders away (the big venom problem here) is to make sure we're constantly moving things around. A sofa that doesn't get moved every few weeks will have a spider behind it. We try to move everything out to sweep every so often, because most insects and arthropods just want to be left alone. And maybe a plus, if these centipedes are carnivores (eating other bugs), if you're keeping everything swept up pretty often there's not much hanging around to attract their prey.
Hopefully someone will appear with some firsthand experience about plants, I've heard some things about peppermint oil for repelling insects but had no successful experiences with it. Probably can't hurt though!