Some actual facts:
The
timetable planning rules published in 2020 say the following about auto-reverse:
So auto-reverse is planned for Abbey Wood - Plumstead sidings,
and for the crossovers on the central section with passengers on board.
It also states that auto-reverse takes 2 minutes, and manual reverse takes seven minutes.
This
report about the train technical specification (from 2015), says the following:
So reversing trains will be tipped out at Paddington, and autoreverse is planned to be used elsewhere including in passenger service.
The driver stays in their cab whilst the train is moving, and then walks down to the other cab whilst the train is stopped, so at no point is the train allowed to move without a driver in a cab