If I was out of work for 6 years and my first job interview might actually get me a job, I'd be scared too. So don't worry about it too much. God is apparently taking care of you and helped you get this oppertunity. I and others have been praying for you, and apparently God heard us.
Access is one of the easiest to use databases out there. Feel free to pick my brain for help, or post any questions on the Database forum here. Many will be glad to help you. I've been using Access since 1.0, way back in 1994, so I got you covered should you need any help. I've helped other people learn Access in the past few jobs that I've had, and have had a 100% sucess rate in them learning it. Plus I live down the street from you, and if you and John have a free evening I can give you both a crash course on Access for free.
Many here cannot find work because they have a skilled IT job that has been outsourced to other countries or replaced by H1B Visa workers. They are being paid more than $7 an hour, and are already experts in databases, programming, etc. Right now you are just learning Access, and are lucky to have found a potential job. In this job market it is like winning the lottery. I am sure as you get more skilled, you will get pay raises and rise in the ranks. I have faith that you can learn Access and any other program that you need to learn.
Remember it is like being an athlete, you must exercise your muscles (brain) so to speak before you can get back into the game. In this case, you must learn how to educate yourself again like you did in college. You have done this before and can do it again. Start out small, lift small weights, learn simple things with Access and when you are ready you can lift larger weights or learn more complex things in Access. Take it one step at a time, take breaks if you have to. But don't quit or give up, keep on going. Even if you make mistakes, you can learn from them. So it really isn't that bad.