Task-oriented dialogue about: train

Can you help me find a train leaving on sunday and arriving by 18:15?
Where are you departing from and what is your destination ?
I'm going from Cambridge to Standsted airport.
Train TR1526 leaves 17:40 and will get you there by 18:08. Would you like some tickets?
Yes, that would be great. I'll need tickets for 7 people. I'll also need the reference number.
Can you book it for me and get a reference number ?