Generally, when drivers 'sign' the route through/to/from a station, they will sign all platforms and lines. This includes the meaning of each of the theatre box indications and position indicators ("feathers"), which lines/platforms they can and can't accept, linespeeds, platform lengths etc. They will also usually receive a briefing on the shunt moves that can be undertaken around the station, and carry diagrams they can refer to (or they can call the signaller on the GSM-R phone).
However, at complex locations drivers will sometimes only learn part of the layout, usually just to speed up the training process - but sometimes it's also because they would never use a certain part of the station. For instance, this could be because it's unelectrified and they only drive electric traction, or the platforms are too short, or the traction they sign isn't cleared into certain parts of the station.
As an example, not all drivers that sign London Bridge sign all of the lines/platforms. EMR drivers will sign the 'high level' platforms at St Pancras but not the 'low level' ones. It's similar to how drivers who only drive freight trains or <75mph stock will often not learn the exact speed restrictions above 75mph, so they might need additional training if they move depots or start to sign higher speed stock.