ARMADA is my idea for the final answer - has to be a 6-letter word (one letter a day for 6 days), and the words so far would contain letters that could lead to it.
Incidentally, the terms and conditions on the MyMail site say that you have to have four front pages from the relevant week's Daily Mail (as in the similar competition last year), but there's no mention of this in the Ts & Cs written in the newspaper.
Also, what a shame they've made the competition so damn easy: no hunting of any kind required!