If you’re booked on a cruise leaving from “London,” it is really departing from Harwich or Southamptom. Either of those ports can be reached from London by train, but the train from Harwich is an especially good option. This is the case because the station at Harwich International Port is especially close to the ship itself. You can be off the train and in your stateroom in as little as thirty minutes if you take the 12:28 train from London’s Liverpool Street Station. You’ll arrive at Harwich at 13:40 (1:40 PM) after the main crowd has been processed and you’ll breeze through check in.
Personally, I think just about anyone would find the train experience to be a much more enjoyable transfer than a bus or cab and it’s more economical as well. Unless you are travelling with a large amount of luggage or physically challenged in a way that makes handling any luggage a hardship, the train is quite easy to board and get settled into.
Also, the Liverpool Street Station is not especially large (compared to Victoria, for instance) and finding your train will be no difficulty. One thing to keep in mind at the station is that you shouldn’t try to access the platform until your departure is listed on the “board” in the main hall; there are two sets of platforms and, if you haven’t waited, you might end up at the wrong set. Incidentally, First Class offers little in the way of amenities on this train and really isn’t worth spending more for.
Here’s a map of Liverpool Street Station.<iframe src="https://www.google.com/maps/embed?pb=!1m14!1m8!1m3!1d2482.7435618920886!2d-0.08231450000000001!3d51.517920499999995!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x0%3A0xc57f7d6c0b61ff5f!2sLiverpool+Street+Station!5e0!3m2!1sen!2sus!4v1407274767641″ width=”600″ height=”450″ frameborder=”0″>