I took it off to see what size socket/torx I needed to undo the plug bolt, I didn't have the correct size so put it all back on.

Few days later, I've got the correct size torx, jack the car up, get underneath, undertray has GONE!!

Obviously I didn't do the screws back up properly and it's fallen off somewhere!

Is it important that I need to source a replacement, or am I fine to run without it?