Should i get bus or train to London from Glasgow? 
flight is 2135 hrs same day
i can get a bus for £9 at 0820hrs arrives at 1730 hrs at London(victoria)
but it is 9 hours of uncomfortable travel.
OR
Train 1 at Glasgow 1140hrs arrive at 1612hrs £40 and plenty of time to get to Heathrow for flight.
Train 2 however leaves Glasgow at 1440 arrives at 1913 hrs London Euston for £30
Can i still make it to Heathrow in time you reckon?
Both trains only 4 ish hrs travel time.

flight is 2135 hrs same day
i can get a bus for £9 at 0820hrs arrives at 1730 hrs at London(victoria)
but it is 9 hours of uncomfortable travel.
OR
Train 1 at Glasgow 1140hrs arrive at 1612hrs £40 and plenty of time to get to Heathrow for flight.
Train 2 however leaves Glasgow at 1440 arrives at 1913 hrs London Euston for £30

Both trains only 4 ish hrs travel time.