We went with Monarch from Manchester last year booked through Jewel in the Crown flight only, was able to get a very cheap last minute deal for 42 days. During a 6 week period in November there where lots of flight only offers so they must have had difficulty filling the plane.
Personally travelling scheduled with any airline and in particular Qatar wins hands down compared with charter, OK it takes a bit longer and you have to change planes but the overall experience is much better, check-in, select your own seats free of charge, in-flight entertainment, food, free drinks and the much more professional way the crew attend to passengers.
You also have the option of days you can travel the ability to change flights and to cancel without forfeiting all the money you have paid. Finally its usually a lot cheaper. So goodbye Monarch no great loss to the Goa route.