Open University Module UCAS Help

I am currently studying an OU Module called Law making in scotland, its only worth 10 credits and its OU level 1. I am also currently preparing my UCAS application. When inputting my OU course I was asked for my predicted grade, however, I don't know what to put. I emailed OU and asked and they literally just said they cannot provide a predicted grade as its my first module and the assignment which would actually get a grade doesn't start until after the deadline for my UCAS application. Am I allowed to just say what I think I'll get as a grade? Furthermore, does anyone know what the grades actually are for this type of course, i.e. a Pass/Fail, A, B, C, or Pass, Merit, Distinction?