Alex whilst you were dealing with a poorly DH, my poor mum got taken ill which totally threw me, as It's not her heart this time. Maintaining a wall of silence in front of DD until after 19th unless there are developments.
You've had more than enough to deal with yourself. Your DD'S school probably see locating the venue as such a trivial thing that they don't appreciate that when you are already under a considerable amount of stress from a much bigger issue, minor issues can be the things which drive you over the edge. You will be able to find it. Get DH or someone else to go with you.