While I can't list the tools required you should replace the water pump when you replace the belt, also check the DM pulley carefully and replace if there is any indication that the inner and outer parts are drifting apart.
1 X timming belt
1 x guide pulley
1 x tensioner
1 x water pump
1 x tube of locktite
1 x fan belt
And some anti freeze
The timming pins are around 20 quid a set and will make the job easier.If its your first time then i would suggest you remove the starter motor to see where the flywheel locking pin goes as its a bit of a bugger to find unless you know where it is ( its a hole next to the starter motor). youve only got 2 shafts to pin up as the diesel pump dosnt need timming up so dont worry if you move it. Book says over 2 hours but if its your first got then give yourself more time
Locking pins - 8mm drill bit and a long handled allen key, can't recall what size now though.
It's fairly simple. The BoL is fairly helpful on this job actually so work methodically and carefully and you should be fine. One thing to note is to make sure the tension is set right. You'll want something to turn the manual tensioner too, I have a bit of 8mm door handle rod and get a spanner on it. Bit Heath Robinson but it works. You will also need to have a jack under the engine as the engine mount needs to come off.
I believe a 52 plate C5 will have the same RHZ engine and I have the BoL that covers the HDi too if you wish to borrow it. I might even be able to assist if you wish.
I did my 2.2 hdi recently, got kit from eurocarparts for 85 quid, they had cheaper kit but this one was an SKF kit (swedish, very good quality with GATES belt )
they also had water pumps at two prices cheaper had plastic impeller i chose metal version