When we terminate people, we do not allow them access to their computers because we do not want to take chances that they will leave malicious files or tamper with network files, etc. We haven't had anyone ask us to retrieve any documents- but admittedly the people we've let go have only been around for a short time. I know that they had personal photos on their desktops but they must have had other copies of them. I would guess that we would be understanding if someone asked to retrieve some files but we would want to be the ones doing the actual retrieval. (i.e. have the terminated employee stand over one of our shoulders) If your company has a specific policy against using company computers for personal use or if they are a larger company, they may not be very sympathetic.
Like gen said: if you need files from your work computer, try to get them ASAP.
Best of luck with everything- I know that this must be horribly difficult for you but whatever happens, it's not the end of the world. (((BaileyCatts)))