Ok so here is the latest update.
I walked into the Air India office on saturday and they checked it on the system and as per them I am fine boarding the flight.
And since they would be issuing the boarding passes for Air Canada as well, they seemed to be confident that I should not be having any issues.
@bryanna: Thanks again for being there to sooth out the nerves.
I have around 3 hours to change the terminals and online support from Heathrow says that It should take around 1.2 hours for the same, so I guess it should be fine keeping in view the time taken to embark from plane and all stuff.
It would be tight but I should be able to pull it off.
The first thing I would be doing after I return from this trip is renew my Passport

Have had enough stress from it then I had from all of my previous trips together.
In case I run into any issue, which I hope i do not.
I will keep you all posted.
Now I am running to pull off routine jobs like arranging the forex, taxi to airport etc. as only 10 days are left for the trip and and I am way way behind the schedule.
Take care guys.
See you all soon.