hi, my freind has a t reg disco and the garage told her it needs a new servo, and that this would be a very expensive job. has anyone out there changed the servo themselves? as i would like to know what the job involves, is it difficult etc. any advice would be most welcome ...thanks

Have a look in the DI workshop manual it's typical on the work required, depends on your skills but it's easy if fiddly.
http://www.landy.pl/LandRoverDiscoveryWorkshop1995-1996.pdf