The drivers door on my 2003 fiesta wont open either from the outside or inside. You can hear the locking mechanism working just wont open. Anyone give me an idea if this is an easy fix or likely to be exoensive, assume the door panel inside would have to come off but could be difficult as I cant open the door

Hi,

It's likely to need a new door latch mechanism, these are fairly cheap used from a breakers yard.  The door-card will need to come off to access it though which is the difficult part when the door won't open.  

There is one free trick you can try first, keep knocking/tapping the door with your palm on the outside roughly where the latch mechanism is, and at the same time repeatedly pressing the lock & unlock buttons and trying the door handle.  Sometimes it shocks the latch to working briefly.

Failing that, carefully remove and save the door card off the scrapper, remove parts needed, then,  if you damage your own door card you could replace it with the salvaged door card, simples..