i know the isuzu is a good motor but in the uk they are not the cheapest for parts land rover parts are not expensive but yeh they still make the 300tdi in brazil or a very close relation to it
that's had it mate new tensioner time but 75 quid is rich they can be had for about 45 two Minuits to change
http://www.ebay.co.uk/itm/DISCOVERY-1-300TDI-FAN-BELT-TENSIONER-GENUINE-DAYCO-OEM-LAND-ROVER-ERR4708-/130711904205?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1e6f095fcd
could be a few things worn ball joints ect, could be the steering box ,the main control arm coming out of the box with the big nut was loose on mine when i got mine,