Thanks, Samyutha (and welcome to the forum).
Advice elsewhere has been "Please follow Government advice and avoid travel by train unless you have no other option" which lines up with that - HOWEVER - this words suggest that bus is preferable to train? Surely not?
Government advise is all where possible avoid all public transport methods. This means as I understand it, you may travel by public transport for any permitted activity if you have no other method. If you’ve got a car available you shouldn’t really use the train or bus... but if Lisa needs the car then graham you may use the public transport as you don’t have a car available