Most all of us felt the way you do now when we first started. The most important thing is to take a step, then another step and keep going. Before too long, you've moved a bit down the path with others behind you. As Meredith said, everyone will be willing to work with you at whatever pace you're comfortable with.
The good news is.. it's ok to suck at Aikido, I do it all the time.

You won't get better by not doing it, and sometimes life does get in the way. Hope to see you on the mat soon. We'll be here.
John