Going to Croatia early September for around 17 days and starting to plan where to go (and not go) and visit,routes,airports, accomodation etc, using public transport and ideally flying in and out of Gatwick, which may be hard to or from some of the Croatian airports. May consider Pula but its 7 hours by bus to Zadar to head south to Split and Dubrovnic and maybe include an island. Would like to fit in some trekking as well as beaches, cities and historic sites. Any recommendations/ideas?