Help with batch file that compares file size to available space

I need a batch file created that can replace a broken backup feature of an old program. I need the batch file to look at the size of the file that will be backed up, compare it to the available space on the F: drive. If there is space, then it copies the file, if there isn't space, then it deletes the oldest file in the destination to make room for a new file.

Basically, I'm backing up one file, once per day, and just need to make sure that that the drive has space before copying. My current batch file is:
@echo off
set mydate=%date:~4,2%_%date:~7,2%_%date:~10,4%
copy /z "C:\Program Files (x86)\Camelot3\Database\CAMDB.FDB" "F:\Camelot\Camdb_%mydate%.fdb

This is just so that I can keep multiple copies of this file