London Gazette
http://www.gazettes-online.co.uk/
Another great site to search for your rellies.
Complete coverage of the London Gazette is provided for the period of the First World War. Printed volumes have been digitised from January 1914 to December 1920 (many of the military honours were awarded in the period immediately after the Armistice).
Complete coverage of the London Gazette is provided for the period of the Second World War. Printed volumes have been digitised from January 1939 to December 1948 (many of the military honours were awarded in the period immediately after the end of hostilities).