The real issue is actually not the train journey (apart from cancelled trains overnight) but the final mile to the terminal. It's being reported today that due to the combination of Govia using some low capacity buses rather than pure bendy buses and the frequency of the service it was taking around 20 to maybe 30 minutes of queuing to actually board a bus to the terminal with passengers packed in like sardines this afternoon. I hate to think what it will be like in the summer.
The service offered by Govia is truly shocking and marks a new low for the airport.