Hey Ant!! Sorry this came in late, but better later than never.
I've been tied up with reading for CFA and I just dug a bigger hole for myself by applying to read for a M.SC in ISE next August.
640 is a good score, remember the gmat only open doors for interviews, a lot still depends on your application essays and your performance on the day of the interview.
It's been great discussing GMAT problems with you, and I hope you'll still be around to have those discussions. Hope to have that French dinner some day! Good luck with your apps, and keep coming back to let us know how's everything.