Sucks Ash, I had the back plate stolen and replaced with an expired one this summer, reported it, and was told I couldn't drive it untill it was replaced (meanwhile I still needed it for work, so I just took the front plate that was in the car and put it on the back), I would be the one in trouble.
Doing almost all the work on my car (including replacing a transmission), I truely hope they find yours, because the idiot(s) that took it I doubt knows how many hours of work it takes just to afford it, as well as all the work you put into it. Good luck, and I hope all goes well.