All of the Disney BOGOF titles seem to be £15.95, which means you're getting them for about £7.97. Buying 2 titles technically takes you over the 30 minimum spend and you get the £3 as well as the BOGOF. That means you get 2 titles for a total spend of £12.94 or £6.47 each.
Apologies if this has already been posted, but I couldn't see it. Don't forget quidco.