From the City Centre the Hammersmith and City line still goes there, if you are coming from the east e.g. Upminster then get the national rail line to Barking (as you should anyway as it is quicker) then the H & C again for two stops. It is a right ball ache getting on after the match they put a fence up for you to que behind for about half a mile now (upton park station), you may be better walking a stop especially as the number of trains will be greatly reduced.