AFAIK the DLR has always been staffed, there’s never been a period where it was truely driverless.

However, as it was designed for automatic train operation from the start, it is effectively “guard (US: conductor) only operation” instead of “driver only operation”, and doesn’t have a traditional drivers cab.

DLR has a passenger assistant who can “drive” the train in some circumstances if required (reports of trespassing on track) but is not for driving and certainly doesn’t always happen.

Only completely unstaffed vehicles in the U.K. that I can think of are short people movers like the ones at airports. Many tube lines can be driven completely automated, the drivers job on lines like the central is basically “push go, hold deadman’s switch, push door close” and repeat, but they aren’t

In other countries on lines which are staffers vehicles there are typically far more platform based staff.