Never travelled on it but my dad works for National Express
When i went up to BHX
a while back i left at midday to LHR
. We took the train (Virgin Trains) to Euston and then got the London underground. However much critisism Virgin Trains have gotten over the past few years, i can say they are very nice, especially if you get one of the new trains, which you probably would. If you don't want to go from BHX
then you go from Birmingham New Street.