Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Belfast to Zagreb as you normally would.
Zagreb Franjo Tuđman (ZAG) is the airport you will fly into if you book a flight from Belfast to Zagreb. You should not have trouble finding flights to Franjo Tuđman from Belfast; the airport handles an average of 0 inbound flights from Belfast per day. You should also have plenty of airline options to choose from since 2 airlines have flights to the Zagreb airport from Belfast. It is only a 6.7 mi journey from Franjo Tuđman (ZAG) to Zagreb’s city center.