Fair use or fair dealing with copyright

Does anyone have any experience with the above topic?? I have a sci fi story where the people in it are creating real stuff out of their imaginations, so the town ends up being attacked by (in quick succession) a series of dinosaurs including a dilophosaur of Jurassic park dimensions rather than its real size, several indominus rexes, Godzilla and Gidorah and a bunch of creatures and people mutated by Resident Evil's T-virus. I'd like to know if there's a way of checking ahead of time whether the way I've written them into the story counts as fair use. It feels like it is, but I'd like to sell the story so don't want to have to deal with copyright wrangling after the fact.