guys, thank you all for your feedback.
i've just been told by my airline that they have confirmed me on the saturday flight (the one i was waitlisted on) so i am now flying on the day my visa runs out.
phew, that's one issue off my back, now to pack two years' worth of built-up luggage and getting it freighted out.
garry, i'm sorry i wont now be able to provide you with a story on an "overstay by a day" scenario. what i will let you know, however, is whether or not the exit controls are in operation on a saturday night
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once again, thanks for all the advice.