I teach as an historian in a non-history department (I have other specialisations) so I understand slightly the imposter syndrome when talking to "real" historians (I being ironic). But you have a perspective they will not have - be clear about where you're coming from.
I've got imposter syndrome about the queer theory bit, because although I research sexuality, I came to it via feminism, not via queer theory.
I teach queer theory (although not the trans*activist rubbish non-reading /misunderstanding of Judith Butler). I teach queer theory to 2nd year students via feminism, and I point out that there are places where some gay male activism has been inimical to women's rights and feminist theory.
If you make this clear, then I don't think there's a problem. I start with explaining in very basic detail, the distinction between sex and gender, and why this is important for feminists and also for Queer theory. And I explain that I"m not talking about "gender identity" (which always sounds to me like an internalisation of that which oppresses us), but gender as a system of power, designed to oppress women, because of our biological role in reproduction.
So then you can say, well, if sex and gender are distinct, and you can name gender as an oppressive social structure, then that opens up a fluid space that's been named as "queer".
I challenge their thinking that they're so cool - the "My best friend is gay" etc etc - I say that that is still putting people in boxes of sexuality; but the idea of queering was (originally) to radically destabilise notions of sexuality as fixed and linked to sex and gender.
The problem nowadays is a lot of people who either don't read this stuff, or misunderstand it (they take Butler's arguments for recognising the cultural structures of science to mean that the verifiable data of science - biology - are just "someone's opinion" - I call it "vulgar postmodernism"). And they mix up ideas about sexuality - where queer theory emerged - into a weird way of justifying men self-identifying as women and being "more oppressed" than women.
The recent battles around trans*activism are anything but "queer theory" - but that is probably all your students will know about Queer theory at the moment.
I teach it as another tool in the way we can interpret cultural production (to use Bourdieu's term).