Zadar is not the worst place to spent a couple of nights.
Failing that, you could fly into Split in the morning, take a rental car either one-way to Zadar (and fly home with FR from there), or return rental with evening flight back from Split.
Would be possible with Easyjet, outbound from STN, LTN or LGW in the morning, and then the Wednesday evening return to LGW.
Last edited by insuindi; 3rd Apr 2015 at 10:35.