As for nutrition - the day before you want to be eating plenty of complex carbohydrates - have a look
here for a list of those foods. That should give you a good store of energy.
On the day, you want food that releases energy quickly so simple carbohydrates for the day of the race
like these.
But, TBH, the body should be able to cope on it's normal intake for the RFL distance - unless you're severely restriciting your calorie intake.
Also - don't go changing your eating habits on the day of the run - you don't want to be runnin on an upset stomach!
Good luck with the race!