£30.70 from Southend stations, so cheaper there to grab a Travelcard & the London return, just make sure your on the 22.15 out of Gillingham and your start hitting home from around half-midnight.
The ground is about a ten minute walk away from Gillingham railway station, which is served by trains from Cannon Street, Charing Cross, London Bridge, London Blackfriars, St. Pancras and Victoria with times to suit everybody, (though Victoria usually takes longer, but you could jump off at Rochester for the better pubs if you can scrounge an afternoon off), and still time for a pint after the game.
To find the services available on the day, go here;
There is some fast services from London St. Pancras that are limited stops but charge more, make sure you get the right service, but at peak time it's not really worth the extra, but an example given below.
Examples (£15 return unless stated)
Cannon Street 16.46 - Gillingham 17.35
London Blackfriars 16.55 - Gillingham 18.22
Charing Cross 17.39 - Gillingham 19.02
St. Pancras 17.55 - Gillingham 18.38 - (£20.50 return only)
Victoria 17.57 - Gillingham 18.50
Getting back (part of £15 return unless stated)
Gillingham 22.15 - Victoria 23.07
Gillingham 22.15 - St. Pancras 23.06 (part of £20.50 return only)
Gillingham 22.24 - London Charing Cross 23.43
Gillingham 22.36 - Victoria 23.37
Gillingham 23.36 - Victoria 00.38 (Last Train)
Give yourself an extra 90 minutes from Southend stations changing at West Ham, (Fenchurch Street for Bank), or Stratford/Liverpool Street depending on how you enter the capital.
Turn left out of the station and follow the road until you come to a crossroads. Go straight on into Priestfield Road. The visitors turnstiles are at the far end of Priestfield Road.
Remember, it's in a Group Save area that can cut fares in half if four of you can travel together, as low as £8.60 each in this case, and any various travelcards will make it even cheaper.
To find out more, go here:
(Thanks to www.footballgroundguide.com for stadium directions.)