Train vs. Plane
If I recall correctly, UK surface public transport pays excise duty at the full rate (that is to say the same as you and I do) on their fuel (diesel predominantly). I think I would be correct in saying that aviation fuel is not just VAT, but also excise duty free - which makes a heck of a difference between the cost of a tonne of road or rail diesel, versus a tonne of jet fuel.
Doesn't really help operators running electric trains though!
So far as the question of relative emmisions between an electric powered train, and an aircraft I would think that dependent upon which side of the fence you sit, you coud make a case for either mode of public transport being more environmentally friendly, using the same data - there lies, damned lies, and statistics you know!
As for comfort, please compare apples with apples, and look at the comfort and space offered even in 2nd (OK Standard) class on a train, and a VLM Fokker - no competition methinks, and you can play with all those elctronic devices so beloved of today commuter on the train.