The good news is that I've been able to access the huge client's server and start work on it
Being able to do that took quite some time and lots of phone calls to and from the client.
Client had told me to use the ip address she gave me but that turned out to be wrong (only she can use the one she gave me). Once I had the correct one I was able to get on the server.
Then when I clicked on the accounts icon on the desktop I was told that I didn't have the required permission. That's something for the server administrator to do but that eventually got done.
Then I found that I can't print off to my printer and the client couldn't really help there. I worked out a way round that by creating pdf files, getting those over to my computer, then printing them.
There was a bit of a holdup with getting files on to my computer but between us we sorted that out.
I'm using a USB flash drive as the means of getting files from their server to mine. I set up my desktop connection to the server so that only that drive gets linked to the server. That way seems the most secure way so that the server can't see what's on my main drives.