Filter life is dependent on the amount of dirt that the engine breathes not a fixed time period.
The 200TDI filters are not the same as the 300TDI. They cross reference to a lot of common industrial machinery and can be purchased at any industrial supply store.
I would avoid the K&N style as they have been tested to have much worse filtration efficiency.
Pissing people off on the "net" since 1983.
Land Rover. Turning owners into mechanics since 1948.