How many hours before or after a booked departure is ticket valid depends on:
- What type of ticket do you have ?
- Where you travel from / to ?
If you have a basic ticket, it is usually valid for a booked time. But for example, when ordering a ticket to travel from Stansted airport, you can see the ticket is valid 3 hours before or 3 hours after a booked journey:
But if you miss your scheduled departure, you can try to take another bus. It will maybe take you, if there are some unoccupied seats.
You can also buy a Change & Go ticket
for an additional fee. With this type of ticket, you are able to board any available coach 12 hours before or 12 hours after your original departure time.