Hello Mick
The injectors on this car are at the back of the engine - not so bad to get to, but a lot of dismantling is needed if you want to try yourself.
The injectors are held in by one nut and a clamp down plate - with these removed the injector pulls out to reveal its copper sealing washer which must be renewed, together with a plastic sleeve that keeps the injector centralised in the hole.
In theory, the copper washer keeps things fuel tight but on rare occasions this doesn't work and the cylinder head has to be refaced in that contact area - not what you want!
Each injector is connected to the next one by rubber leak off pipes - these take uninjected fuel directly back to the tank. Its worth looking at these for leaks too, before you get stuck in. Measuring the amount of diesel leak off by each injector is probably the only way of analysing injector performance on common rail systems, and you are in to specialist territory here.
Maybe this info will help you decide which way you want to go.
John