From where the lift drops you, second car closest to you (right hand side of the train).

Far side meaning opposite doors.

However… when I went through T4S earlier this month (17/5) they'd placed (rather pointlessly) tensa barriers BEFORE the escalators to separate the queues to get up the escalators into non-EU and EU lanes. So the car trick doesn't really save time now and if the tensas are still in place I would want to be on the far left side of the train as far away from where the lifts drop you.