I didn't do short story (i did critical response) but from watching my friends there is considerable research involved and you won't get away with it if you just "crap on" because that becomes very evident in your reflection statement- and yes, that's marked by the BOS!
I'm not sure what your idea is so I can't tell you specifics of how to research but here are some tips;
-if your story is based in a particular genre eg. fantasy, then read up on that genre and it's conventions (oh god, eng x1 flashbacks..)
-If your story is set in a different time or country read up on that and do that indepth because it you don't it will make your story less realistic
-If your story is in a particular style read authors of that style for inspiration
-Go to workshops, read books etc on how to write. I'm sure you know but to do well in eng x2 you need to know how to write well. Any tips on characterisation, effecting setting etc won't hurt
And yes this research will pay off -you'll have a fantastic final product and a great reflection statement!