Micro Plus 501 Hatch?

I am looking for a boat hatch for Micro Plus 501...can anyone give me any tips on finding one? Absolutely devastated ours fell off the roof into the lake while we were eating, when I do find one again its definately being attached differently so it can't fly off lol but first problem is finding one??? We have literally just bought the boat so are desperate to get it sorted so can get out a few more times