No reason to be scared to train with them - I think that you'll soon find that strongman competitors, while some of the biggest guys out there, are some of the friendliest folks to get together to train with. It seems to be a common thread that most are so excited just to have new people with interest come to join in, you'll probably feel at home after your first time there
Training took a new direction for me, turns out I've got 3 severely compressed discs in my lower back, so I'm on a 3-month recovery program to try and fix the problem (or, at least severely lessen the pain factor through rehab). Won't be squatting or deadlifting anything more than bodyweight until the end of spring (and won't be doing ANY regular squats or deadlifts for at least 4-6 weeks), so it's upper body mania right now just trying to keep busy.
Hope the session goes well with the big guys whenever you get out there!