Did you check out easyJet? Their last flights from Heraklion to Edinburgh in October are on Tuesday 25th and Saturday 29th.
Or Jet2? Their last flights on that route are on Friday 21st and Monday 24th.
On the Heraklion to Glasgow route, Jet2's last flights are on Thursday 20th and Tuesday 25th.
Thomas Cook's last flights on that route are Tuesday 18th and Friday 21st. (Thomson cease flying on that route after early July. Ryanair's last flight this year from Chania to Glasgow will be on September 28th).
Going via Oslo sounds fun though!