Talk to your tutor! This was one of my biggest panics as I'm doing an access to HE too, but my tutor said she was happy to predict grades for me based on my first completed assignment.
Also, are you sure you're getting the numbers write? Access courses being 45 units @ level 3 in total; only requiring 1 distinction and 2 merits seems bizarrely low...and also impossible, as each assignment is worth at least 3 units (at least it is on social sciences, and I know it is on forensics & psychology, which a friend of mine is doing); or do you mean 1 distinction as in...1 assignment graded at distinction (which may be worth 3 units or more?)
Either way, talk to your tutor and explain your situation to her and ask what you can work out together in terms of your grade predictions.