can someone tell me how long it take to change and replace the high pressure diesel pump on my 3.0 litre diesel 2003 range rover been quoted 8 hours labour is this right and its the pump at the front of the engine??

The pump is on the front passenger side of the engine near the top, its a bit obscured by the engine covers. It is driven from the engine timing chain. I am no expert but would presume the rad, fan and belts would need to come off to get access and somehow the timing chain tension released to remove the pump. I think there is a special tool to release the gear from the pump in situe so the timing is not effected but not sure how that works A days work does not seem excessive but the tool might save a lot of time
Look at the attached video at 36secs in,
https://www.youtube.com/watch?v=faxlECHCKWU

 2007 TDV8 VSE
2003 TD6 gone.
2002 P38a gone
1999 P38a gone
1997 p38a gone
1993 VSE gone
1992 VSE gone
1966 Series 2a with V8 conversion gone

when its put like that it does seem a hard days work not for the faint hearted

It wont hurt to get a second or 3rd quote, even try a BMW independent. 2007 TDV8 VSE
2003 TD6 gone.
2002 P38a gone
1999 P38a gone
1997 p38a gone
1993 VSE gone
1992 VSE gone
1966 Series 2a with V8 conversion gone

Hardest part of the job is getting the viscous fan off