Fuel Gauge Not Working

[Nocky]

Hi all, new to forum, recently brought a V reg (2000 registered) Terrano 2.7 Tdi S LWB 94,000 on the clock, (now wife, kids, mother and mother in law can all go on trips together! and yes i still have to drive) when i brought the car i was made aware of the usual terrano faults, digital odomiter fading in and out, cured this by removing unit and checking all connections seated correctly, when i brought it i put £60 diesel in it as fuel light was on, tank then went to full, have done approx 130 miles in it and now gauge is on empty and will not move, after alot of web trawling i have found it is either the voltage regulator? if it is i dont know where it is or the fuel sending unit? (guessing the risistor is worn or the float has a hole in it) in the fuel tank, would this be correct, not sure if it is a mechanical or electrical unit, any help or advice would be welcome, sorry for the long 1st post, thanks in advance to anyone with any advice