Southampton/London Rail Tickets, In Advance?

Do I need to get rail tickets in advance (Southampton to London). If so, how do I determine the time we will get off the ship?

Pre-booking tickets can sometimes be cheaper but you don't have to book ahead in order to travel.

If you travel to Waterloo, there are no cheap advance purchase fares if you buy normal fares - they are all walk-up fares. That is what I always do - very flexible and really not that expensive at the end of the day.

You can buy cheap advance purchase tickets from Megatrain on this route, but they have a very limited selection of trains to choose from, none of them are the fast trains, and the tickets are inflexible.

If you travel to Victoria, I think that there are cheap advance purchase tickets. But the trip takes double the time taken by the fast train to Waterloo, so I don't recommend it.