Probably your best bet is to go ahead and book yourself a one-way fare, as your chance of IT taking care of you and rebooking you onto another airline is very, very slim. Mallya has grabbed the money and run already, AI will most probably be death coming May. (And even if not, they won't be in a hurry to try to bring those people stranded by their fault home..)

Good thing for you is, One-Way fares appear to be still quite cheapish, 8th May showing as low as 343£ from LHR. That's with Gulf Air, an airline you might prefer to avoid, as well as the 349£ for Air India, but for as little as 356£ you can fly with Turkish, which is a very good carrier.

Direct flight from LHR with Jet would be 384£.

Flights on other dates in May could be had for a few pounds less, but not much.

Best offer from Glasgow to Mumbai is for 435£, basically the same flights from Jet as above, with the connection to LHR by BA, for the additional 50 Quids or so.

Emirates would be 457£ - if you prefer to have the "short end" of your connection at the end, go with this connection, besides that, there is no big difference in time needed.

Next time, probably better to invest a few £ more and choose a reliable carrier over the "King of Good Times" - as you can see, all the "Good times" have left you is headache, the regular ending of a "Good Time" night