UK Car Repair: vauxhall astra 1.6 ls 1998, vauxhall astra, drive train

Question
my petrol gage isn't working or the petrol light? i ran out of petrol today thinking maybe the light would come on even if the guage didn't work!! how do i fix it please or how much am i looking at to get it done? and i have a knocking noise when i pull off and brake ,or when i have just braked then pulling off,like a cracking noise? please help its driving me mental,many thanks chopper

Answer
First check the fuses, although usually, all of the gauges have the same fuse. Otherwise it would seem like something is disconnected,  can you get under the dash or near the wires that go to the sender unit in the tank?  As for the noise, something in the drive train is loose or worn, take it to a garage ASAP and get them to inspect it.