Reddit reviews Modernism: A Very Short Introduction

Dubliners might be his most accessible work, but I think if you're interested in Joyce as a modernist, then Portrait is a more explicit display of the methods he would develop.

Also OP, I'd recommend Modernism: A Very Short Introduction by Christopher Butler. It's cheap, easy and can be read in an afternoon.

I've read an extensive amount of Romantic poetry, but I've never found Bloom to be particularly insightful. Most of his insights tend to be shallow or tangential, and he likes to simplify things to basic historic trends.

If you are not interested in English Romantic poetry and do not intend to read any of it, I would suggest you look elsewhere for a good book about novelists. I don't know offhand of any Grand Theory of Prose a la Harold Bloom encapsulation, but books such as this about specific subject matters may prove amenable to your interests.