Don't know if you've taken the course yet but......
I just took the CELTA in April 2009. The essays are not that difficult. If for some reason they are not acceptable you will be able to resubmit them by responding to your tutors specific comments. Trying to get help from an on line source will defeat the whole purpose and knowing the content of the essays outside "advice" would be a hindrance and not a help (the essays are very specific to either students you are teaching, your own experiences, or relate to specific content given by the CELTA course that changes from school to school) If you want to get the most out of the CELTA course, just dive in and don't worry about getting outside help. That's how you will learn the most and become the best teacher you can.

Good luck