Hey Belle ~
I agree with Manti's comments. Additionally, if you are a cold water weenie (like me) then an Olympic distance swim in 65 to 68 degrees is miserable. Where I live, it is possible to rent one (or maybe you can borrow one, as Manti suggests). If you borrow or rent, be sure you have enough room in the shoulders and neck. Of course you don't want too much room either. If possible, try out the rental or loaner before race day.
On your dry run (or would that be wet run?) with the wet suit, try to notice any hot spots where the wetsuit rubs. Typical areas are around the neck and around your arm where the seam of your business blouse has the sleeve attached to the main body.
Let me know how the wetsuit testing goes.
Thanks guys! Based on your comments I am going to rent (possibly buy) a wetsuit. It's not a sprint and I am absolutely, 100 percent a cold-water weenie!
Depends on how long the swim is and how strong a swimmer you are. If you are a strong swimmer and this is just sprint TRI, than probably wouldnt worry about a wet suit as it will take you as much time to strip out of it as you will realize in time savings from wearing it....
However, if it is a longer swim, or you are not a great swimmer, than the bouyancy you get from the suit will benefit you greatly and is worth the rental (or ask around, someone you know is bound to have one that will fit you).