I personally think that when your wife signs you up for a race to impress one of her friends, on short notice, you would absolutely NEED a trip to the bike shop with her credit card to "make sure you are ready".
Other than that, ride tomorrow like a light recovery day and get plenty of rest. I've never been a believer in gorging on pasta and bread prior to an event, but a good complex carb breakfast (hot and waiting when you get up) would be in order.