I don't think it's a coincidence that the only viewpoint you get is that of a middle class bureaucrat. It's the assumed audience, and it's where Orwell would place himself as well. The narrative loses a lot of impact if you align yourself with the proles. Winston could live a real life if he really wanted to. I don't think this point is intended by the novel.

Isn’t Julia a member of some sort of anti-sex league, meaning there’s a lot of bad faith involved in their relationship from the get go?

That's a problem in itself, don't you think? It's all very "Feminists hate sex and they want to erase the differences between the genders". Julia gets a taste of freedom and her right place in the world by putting on makeup and girly clothes and having a lot of sex.

Her lips were deeply reddened, her cheeks rouged, her nose powdered; there was even a touch of something under the eyes to make them brighter. It was not very skillfully done, but Winston’s standards in such matters were not high. He had never before seen or imagined a woman of the Party with cosmetics on her face. The improvement in her appearance was startling. With just a few dabs of color in the right places she had become not only very much prettier, but, above, all, far more feminine.

Also she's a flighty moron.