Yeah, you're gonna be alright, hun!
I, too, was never much of a 'man.' I did do things like kill the bugs, hold the door open, etc. but I also do the dishes, vaccuum, laundry, ect. I don't know exactly what the husband is 'supposed' to do, because it really seems like they just sit and want to be left alone or something :/
And if she never had to greatly rely on you before for man-ish things, then your relationship dynamic won't really change at all. As I told my wife, it's the context that changes. Example, I will still set-up the tree and decorate it on Christmas with my wife, but this time, I'll just be a woman while doing it. It does matter, but it's not turning something beautiful into something ugly like people may fear.