I rate attachment theory pretty highly and would say, if you can’t access parenting courses based on this stuff, you still might find some good books in the library for parenting strategies based on attachment theory, and also Google scholar if you’re feeling super academic and wanting to get nerdy about it.
In contrast, the worst parenting course I ever did was one that was hosted by community do-gooders which based their techniques on ideologies around what they believed were the socially accepted family values that all people should adopt. It was not culturally appropriate for a lot of reasons and just awful, so when it comes to parenting courses do your research before jumping in… And when parenting gets hard, which if often does, or you feel like you’re out of your depth, getting advice from experts is fine, it doesn’t mean you need some fancy label or clinical diagnosis, sometimes an outsider perspective on family dynamics in general can be pretty helpful.