Elizabeth, congrats on signing up for your first
its a fun distance to run! I'll bet you can probably do it now (since you're fit from the 5k's) but depending on your goals you might want to increase your long run distance a bit. Going longer in training helps give me confidence to run hard during the race, but I can be a bit competitive ;-)
Enjoy the training and best of of luck on your race!
A ship in the harbor is safe. But that's not what ships are built for.