The plot thickens. I've been up in the loft and after much searching I have found a letter with a few details on it, it wasn't exactly what I was looking for but I shall see if this means anything to anybody on the Monarch page.
Departure Friday 11th October 1996 (unknown time, but we had to leave the school at 0830hrs sharp and it is at least 400 miles/6.5 hrs travelling time to LGW by road), on-board late-evening meal provided, flight MON1504 LGW-ATH
Arrival (unknown date, 7 or 10 days later) 0715hrs, flight MON1505 ATH-LGW
I'm intrigued now!