Also when i clicked through on the email it took me to a page that i think said that travel had to occur between 6 and 20 october, but in the first few lines of the email it said this, which is slightly less restrictive if it actually governed the offer...
"Book your flight by 18th October and begin your travels on or before 19th October 2011"
Which would mean you don't have to be back within 14 days...
Definitely wish this offer was available next year but lets hope there is another european city added by then...