If your boiler is running fine, you may think you will leave the servicing for the time being. This could be a false economy.
Your boiler is like your car. It needs a regular MOT. During a year of general use deposits build up inside the boiler which can reduce the efficiency of the system leading to higher gas or oil bills for you.
In the case of all boilers it makes sense to have a regular check for safety reasons. Although modern gas and oil boilers are unlikely to have safety issues there is always a small chance that something can go wrong.