Renault traffic 01 plate fuel guage not working?

Hi i recently purchased a Renault traffic 01 plate diesel van, however the fuel gauge seems to be on reserve at all times even when i put diesel in it. Any ideas on what the problem is and how to diagnose it. A few people have mentioned changing the instrument panel, also the fuel guage sensor in the tank which cost £200 from Renault or the wiring. last but not least is there a fuse for the instrument panel and where is it located as my speedometer is also not working but i rather fix the fuel gauge first.