I have been getting some feedback recently from a beta reader in the U.S, and they keep suggesting I join words. Two, that I remember just now are, court room, and love making. Oh and another is 'straight forward'. Is this an American thing?
I swear I just remembered reading this, but I believe those are all words that are meant to be hyphenated—but in the US, we tend to drop the hyphen and just mush the two together for various compound words & words with prefixes. Like coordinate, cooperation, preschool, breakup, courtroom, nationwide, etc. There are exceptions, like with proper nouns in compound words but generally Americans avoid hyphens in most situations.
I think you're right about coordinate and cooperation being hyphenated sometimes in UK English. Not sure about the other ones, but I think I've seen the first two hyphenated in UK before. Either way the publisher will have its own editorial standards if the story makes it that far. Pretty easy fix so I wouldn't think they'd drag you over the coals for doing it "wrong," but I could be wrong about that.