emmett: I use a laptop too. And a press of spacebar scrolls down the page (at least on Opera). PageDown should do the trick too.
Rereading your post tells me I may have missunderstood. So, if what you want is to just press Enter when the page displays, without having to scroll down, then I guess all it takes is for Fencer to change the focus to the Submit Button when the page loads. Then, simply pressing Enter (or spacebar) would 'click' it. However, if implemented, I'd like this to be an option, since I like to use spacebar to scroll the page down...