I left recently for greener pastures and if you drop me a PM I will discuss it with you. I found HR to be very very helpful and the company was, as always, very supportive.
I would strongly advise you to cancel all credit cards now as the bank will require at least 6 weeks to ensure that there are no further charges.
HR will give you a list of departments to get a sign off from and this is self explanatory.
Buy all you SRC tickets now as once you resign you have to pay cash and that is a lot of hassle for various reasons. Also if you have any refund tickets cash them in now.
You will lose your ALT tickets so, same story use them now.
Make sure you inform the school of your intentions or you will be charged for a whole term!!
The company let you keep your phone and mobile till the last minute which is really helpfull.
All in all a pretty painless experience made easy by the hard work of a few dedicated professionals in HR and finance.
Good Luck
Mick