I have to make a trip this weekend to Boston from India. The flight that suits my times are as follow:

Jet airways 9W122 DEL LHR Sat may 11 Departure 1:45 Pm Arrival 6:30 Pm
20 Hour 35 min layover
Virgin Atlantic VS011 LHR BOS Sun may 12 Departure 3:00 Pm Arrival 5:35 Pm


Questions
a) I do not have a valid UK visa, but have had on in the past so can i get a UK visa here in india within next 2-3 days? (Since i have to leave in 5 days, i can't risk having my passport stuck with UK embassy at the time of travel).

b) Is there any way to get on arrival visa on indian passport when i am en route to US?

c) In case getting out of airport is not possible, is this 20 plus hour layover doable? I mean, are there hotels and other things to do (casinos may be)?


it looks like, i am going to have to take this flight because i can't afford to fly on weekdays and any other option is around $400 more expensive than this.

What do you recommend?