first sportive advice needed

Hi all im doing my first sportive in a couple of weeks time its 82 miles on flat but windy fen roads im capable of doing the mileage but want to improve my chances of a doing it in a decent time .im eating healthy and going gym and swimming also about 12 mile daily cycle commute unfortunately I dont have the time to ride more than about 50 miles on the weekends.
is thare any activities that I should concentrate on over the next couple of weeks and when is best to stop to recover in time , also what should I be eating the day before and on the day , I understand feeding stations are there but have no idea if that should be treated as a top up or not .
Sorry if these questions have been answered all ready I looked first but possibly in the wrong place, many thanks