This is a very easy pattern. Im sure you will be successful and there are plenty of helpers that have already made them to help you along if you get stuck.
As for the thickness, it is about the thickness of a quilt when sandwiched together. Mostly you will be sewing through a layer of interfacing and a layer of fabric.
The thickest part is the handles and top stitching around the top, there will be a couple layers of fabric and interfacing at the point where the handle is attached. Otherwise, not very thick at all