I am confused, when did you start school? If this is your first year than how do you know if your grades are that much better? You are in for only a few weeks, basically the easy part of the semester so far where the weight/percentage of the grades are probably less than 10%. A bad midterm where the weight is 30% and you might be saying my HS grades are way better. Not trying to offend you, I am just saying that for my kids if I asked them how they were doing after a month it would be Great, I have all As and a B, once the mid terms came around there were more Bs and maybe even in a C.
Just my guess is that since they typically request an official transcript, which means in a sealed envelope you will have to submit your final high school transcript.
Call the MoC office and verify with them if it is an official transcript that is required. They are the ones that will have the concrete answer.