The park and ride on the website says it’s a 50 minute drive and 20 minute walk away
I thought the Park and Ride is at Barleylands? If so, under normal traffic its only about 20 mins away. If they’re stating 50 mins, that suggests they’re expecting Basildon/A127/South Benfleet to be grid locked. So driving won’t be much better!
The 20 minute walk is probably similar to the queue a friend of ours experienced for the rowing at Eton Dorney. They had put on transport from train stations and then dropped everyone off at the start of a 1km, 10m wide path where they were essentially queueing to go through the security. But it was moving, so a much nicer atmosphere than say, an airport. I guess it took 20 mins to get into the barriered part of the venue.
The timings will be conservative to try and encourage people to get there early, not to miss anything.
Even by public transport, I think the train station is 2 miles from the venue, so there is probably a similar bus journey and ‘walk’.