Avallon, welcome to the forum. I assume you have the 1.3MJT based on the info above as both the 1.2 & 1.4 have an oil change each service AFAIK.
The requirement for servicing is every twelve months/18000 miles whichever comes first and if you have only covered a low mileage then there is a provision for that, just tell the service department when you book it in.
Also, if the oil light does come on it doesn't mean the car needs a service, just the oil and filter changing. Basically you have two service schedules on the diesel that don't need to be in sync, one for oil and one for all the rest.
With regards oil changing, on the diesel there will be a warning message along with a flashing oil light to tell you when it is time to change. How soon this happens is based on the type of driving you do.
It is theoretically possible to drive for two years without the light coming on, at which time you would have it changed and the ECU reset to show this but a lot of us have had it appear at varying intervals/mileages, some quite low and others at 10000+ miles.