Format>Cells>Number>Custom
In the white pane type ddd dd mmmm yyyy
Enter a date in the cell, e.g. 01/01/2006
This will show as Sun 01 January 2006 (you choose how many spaces
you want to show between each element, or whether you want hyphens
between 01-January etc. by the way you set that initial format
Drag the cell across or down and the dates will increment.