Hi Malcom64
If you are a new owner (as in this year having completed after January 1st 2009) you won't have to pay IBi tax until next year - as I believe the owner as at 1st January is liable to pay for the year (jan-Dec).
All IBI bills show the cadastral value - if you check out this thread you'll find information about emailing the local authority about the IBI bills, etc., that Michael has posted.
So if you completed after 1st January 2009 it is my understanding that you are not liable for this year.