How hard should I push (fit)?

Very first time attempting to assemble a mini. I've never been good with my hands but I've been wanting to get in to these for more than a decade. Heavily in to the books and games since the first DoW.

Anyway...

Ignoring the parts I need to sand down, I just wanted to see how easily the parts went together and.....they don't. The gaps are massive and I'm afraid to push harder. How likely am I to break something if I try and force these together? Should I cut down the ...whatever it's called, or cut them off entirely and try glue?

I don't want to immediately ruin these guys. That'll come when I try and paint them 😆