All depends what was done on last few services but if your doing it yourself the parts are os cheap may as well do most of em. you'd wanna change Oil Oil filter Air filter Cabin filter Diesel Filter Check brake pads for wear, and brake disks for wear, can do this by eye normally, or when its jacked up a bit Depending on when it was last done , might also need other fluids changed like brake/coolant I buy my parts between Halfords part service and euro car parts , some parts are cheaper on one then the other, ECP lets you just pop the reg in and browse by category which is handy. Depending on weather they have ever been changed , those glow plugs might also need doing and are fairly cheap £6-8 each ish After doing all that i usually take it for a Blast down the motorway and force a DPF regen to but dont think youd have one on 2005, could be wrong though Grab ya self a haynes manual to normally about £20 ish , will show you how to do pretty much everything, will pay for itself in one use.