danj:
am a new driver and have to use digi tacho for 1st time on tuesday anyone got a simple heads up on how it works idiots guide would be great please.
The first link is reasonably straight forward 
Siemens Digital Tachographs - How to use them - Printable download
The Tachomaster Drivers Guide To The Digital Tachograph
DRIVERS SHORT OPERATING INSTRUCTIONS —Siemens DTCO 1381
Stoneridge Digital Tachograph - SE5000 user manual. (PDF)
The digital tachograph simulator
Digital Tachograph Simulator Direct Downloads
Install “Interactive Digital Tachograph Simulator” first, then either or all of the training sequences.
Interactive Digital Tachograph Simulator v4.exe
Training sequences for the Actia tachograph (V 4.0)
Training sequences for the Siemens tachograph (V 4.0)
Training sequences for the Stoneridge tachograph (V 4.0)
You can now run the simulator on-line (links bellow)