What do blokes actually wear? Everything I find is womenswear

Every guide, every photo, every shop page I look at seems to be aimed at women. I am not complaining about that, it is clearly where most of it is, but it does mean I have no idea what the equivalent is for me.

What do men here actually wear? Is a full suit the default, or is that the extreme end and most people are in something less committal? Is there a men’s version of the sensible first purchase everyone recommends?

I am in my thirties, fairly ordinary build, going to my first proper event in the autumn and I do not want to turn up having got it obviously wrong.