"All unions are corrupt, that's why America got rid of them."
Actual words I heard a friend's husband say yesterday.
Because I'm an idiot all I replied was "They got rid of unions so they didn't have to pay their workers. It's not really a good thing."
So yeah I'm pretty sure my friend's husband probably hates me now lmao. 
I fucking hate the narrative. I hate how easy it is for the media to get people to believe dumb backwards shit, because no one it taught properly about anything anymore. An entire population of the easily grifted.
It's basically to check your local trades hall website or actu directory. I've been in one union my whole full-time working life, and they have a strong presence, so I don't think I've ever really been in your situation/know what advice you were looking for, so it was presumptuous of me to assume you werent already informed/researching. However if you're already organising and in contact with your representative union then you're already off to a good start.