Originally Posted by
FocalLength
A local speaks:
If you're still keen to fly, perhaps as you hint because you'd like the extra points and avios, or just for a change, take your taxi to Bradford Interchange station rather than Leeds (infrequent but decent services also available on bus routes 737 and 747). It's a shorter ride and you'll end up on the same trains but only one 12-minute stop away from Halifax.
As another local, this was exactly what I was going to suggest doing!
Travelling to Leeds station and taking a train from there would add unnecessary time and cost to the journey as the trains from there pass through Bradford Interchange enroute to Halifax. Thais said, the trains on that route are pretty grim and packed-out 2 or 3 carriage Northern Rail services... so I would avoid them at peak times!