If your confident in diy servicing then go for it mate.
I do my Lag II every 9k as follows due to the money I save..
Filter ( only tricky part is removing the
engine tray )
Spark Plugs ( buy genuine renault )
Pollen Filter ( buy genuine renault )
Fuel filter is located within the petrol tank and does not generally req changing.
Costs me around £40 for the parts and about 1 1/2 of my time.
If any RF Member wants to drop their Lag II at mine on a Saturday I do it for you and show you how..
As said above the checks are important but TBH mostly you can check the obvious things
Fluid Levels ( you should do this regularily anyhow )
Brakes ( Lags with Alloys make it easy to check your pad depths and disc wear )
Only thing you'll be missing is a dealer stamp..
However if your car is still under warranty pls make sure the Renault Techs do the job..