I see that Jet2.com has been publicising its flights to Dubrovnik (see link here), from most UK airports excluding London . They also fly to Split from Manchester, on Saturdays only from 2nd June until 6th October.
This opens up the possibility of visiting the islands by flying into Split and returning from Dubrovnik (or vice versa) – see link here for some ideas.
But we find Skyscanner to be best for researching flight options.