I don't work there, but know the following was the case a few years ago:
Eurostar:
'Prep' the train. Then Brussels, break, prep the train and back to St Pancras.
or
Prep the train, Paris, break, prep the train and back to St Pancras.
Prep the train, St Pancras to Marne-le-Vallee, break, empty to Gare du Nord, prep the train, back to St Pancras. Or the reverse for the afternoon job.
There were a couple of 'pass' to Paris/Brussels and work one back.
There were a couple of 'lodge' turns - prep the train, work to Paris/Brussels, stay overnight in a hotel, prep the train, work back to London, think one job had a take it to Stratford empty and taxi/tube trip back on the end.
The trains need a prep before each trip through the tunnel, rather than the once a day that all other trains in the country get.
Sometimes the break is longer and they come back with a different set to the one they went out with.
Sometimes the duty has a taxi or tube trip to/from Stratford Depot to fetch/take a set to/from St Pancras at the start or finish of the duty.
Sometimes the 'prep' might be done by another Driver at St Pancras meaning the booking on time is later. Strangely, the turns of duty are different on different days of the week with regard to who preps a train, how long the break is and what train is worked back, and who has fetched/taken it to/from the depot, presumably to average out the duty length over the week.
Quite a lot of long night shifts of 10-11 hours (most out and backs to the Continent are about 7 - 8 hours, although there are longer ones such as the trips to Marne-le-Vallee) and quite a few 'shed and ferry' day shifts as well. The night shifts take 2 or 3 trains to Stratford and bring back 2 or 3 the morning with a taxi shuttling back and forth to get back between each one.
Two links (railway term for rota) at St Pancras with SNCF link doing trips to Paris and Marne-le-Vallee, and the SNCB link doing trips to Paris and Brussels (knowledge of extra rulebook needed).
In the UK, Drivers are drivers, and Train Managers are train managers (I think there's two grades of these, with one occupying the rear part of the train and able to drive out of the tunnel in an emergency).
The Continental crews used to take turns being Driver or Train Manager - not sure if they still do.