Just had an email from Olympic that I thought I would share with you
The sale, for one day only starts at 1 minute past midnight (Saturday night / Sunday morning), and gives customers an extra 15% discount on top of all our other discounts.
In order to qualify, you need to go to http://www.olympicholidays.co.uk
(follow deal link) where you need to follow the Facebook link to sign up. They then click on the link (on the Facebook page), this will return you to Olympic Holidays and activate the additional discount.