Arriving in Mumbai at Midnight - where can I get an airticket for an 11.40 flight?

I will be landing in Mumbai at 00.15 and am planning on catching a flight at 11.40 on the same day. Should i buy the ticket here in London (v.expensive) or is there somewhere I can get it in Mumbai? Airport? Also, anyone know of anywhere that i can crash for a 'half day' as I really dont fancy spending the best part of 12 hours hanging around in the airport!

Thanks

Indianflower

Which Airline?
Both Jet Airways and Air Deccan tickets are available on the net.
Jet Airways has a counter both at the international & domestic airport.

Also, what is your budget for the hotel stay?

I don't know how it is today but Mumbai's domestic airport used to have retiring rooms which were supposed to be economic. There seem to be a number of hotels more or less near to both terminals, understandably not the cheapest in an expensive town. Mind you with getting on and off your planes & getting to the hotel of your choice you might find the better part of those -12 hrs. already filled. As for getting an immediate ticket on the spot that would be anyone's guess anywhere in the world I imagine. It might help if you can tell people where you plan to fly on to. I assume as airports go the respective airlines would have a counter that you could have a go at, although again with the nighttime....

Don't wait till you get there to book your flight. Do it online. It won't be any cheaper in India. "Cheaper" depends on your nationality, not what nation you are standing in when you buy the ticket.

Thanks everyone for your replies. I will be attempting to fly down to Trivandrum on the same day. So far, it looks like only Jet and Indian Airlines fly there from Mumbai.