Task-oriented dialogue about: train

am looking for a train. The train should arrive by 18:00 and should go to stevenage.
Can you provide me with your departure site?
I am departing from cambridge on Tuesday.
There are many options available. Is there a certain time you would like to leave?
What one gets me there before, but closest to 18:00?
Train TR5343 arrives at 16:10. It is the closest to your required arrival time. Would you like to reserve any tickets today?
No, I have decided not to book today, thank you, goodbye.
You're welcome. Have a good day.