Right then.
There's a few places where leaks could occur.....in the pipes from the filter to the pump, the leak off pipes coming from the injectors returning to the pump and then returning back to the fuel tank or from the pump body itself which is naturally more of an issue.
If the leak appears to be coming from the belt cover, left hand side as you look at the engine, this has the potential to destroy the timing belt, and then its bye bye motor.
If the leak seems to be coming from one of the pump body seals then its a replacement pump I'm afraid - these things are built under clinically clean conditions.
Give the pump a thorough degreasing and come back to us with a photo if you can.
John