I have just done mine (200tdi) after the belt snapped.
I ordered all the parts separately from paddocks, this is the list of part numbers I used:
ERR388 - water pump gasket
ERR1195 - timing cover gasket
ETC8560G - idler
ERR2530G - tensioner
ETC8550 - timing belt
ERR6490G - front crank seal
ETC4154G - timing cover crank seal
(if you have a defender 200tdi you will not need the idler, that was disco only)
I used OEM idler and tensioner and seals, both the idler and the tensioner were Britpart packaged OEM. The belt I used was Dayco which is also OEM.
The first time I did mine I bought a timing kit which included all the timing pins and a crank damper puller (
link). This is well worth it for the price, more for the puller than the pins.
I also bought the crank locking tool (
link) as I did not fancy the wedged bar and start the engine method!
I was given by my old work an old torque wrench that is enormous and goes up to 1000Nm was used for HGV wheel nuts). I use this to torque the crank bolt on refitting, but it is possible to rent large torque wenches to get the 333-350Nm torque required.