sdc = service delivery centre, there are two on the tl route one in west hampstead signal box and the other in east croydon, i believe there is only one on the gn side and this is at kings cross, the are responsible for trains running, stock alterations after failures , disruption planning and that sort off thing.
the three day induction introduces you to the company and first, telling you about there values and responsibillities, sorting out your staff travel passes, uniform , pay, and so forth.
hope that helps and welcome to FCC.