Find out what you correct postcode is. If you don't know your 
postcode use the postcode finder at
www.royalmail.com
Enter your postcode in the post code box at
www.streetmap.co.uk
At the bottom of the map it will give you your Longitude/Latitude.
Go to the
Amsat UK 
website and access their Long/Lat to IARU Locator Converter which will calculate 
your IARU locator and display it. 
 
   
   
WAB Square
To work out your Worked All Britain Square look at the LR 
reference number given on Streetmap.co.uk.
Click on convert coordinates and a table will be displayed. 
     
In the Table on the left hand column look for the characters LR 
next to them you will see a Alpha numeric sequence similar to this one - SU507670
 
The Worked All Britain reference is formed by the two Letters 
and the first and fourth numbers. 
In this case the WAB Square will be SU56.
 
       
      Locator Calculator
      
      Click 
      here to use the NGR to IARU Locator written by Neill Taylor G4HLX