The CR signals website (www.crsignals.com) is proving potentially ruinously expensive. They have a much larger range than Berko, including a selection of route indicators. These come in in a range of positions (numbered 1 through 6, corresponding to 11 o'clock, 9 o'clock, 7 o'clock, 1 o'clock, 3 o'clock and 5 o'clock respectively) to indicate which upcoming junction the train is about to take - see Wikipedia or Railsigns.co.uk.
AnyRail doesn't have symbols for any British style N gauge signals, so I've had to approximate with some Pégase symbols.
At £14 per signal and £10 per route indicator, they dwarf the costs of the Arduino and driver circuitry. Sadly, though, I don't really have the fine motor skills to build them myself. The little brass ladder must only be 3mm across!