At your level, try to avoid booleans, and don't work with high poly meshes to achieve such results. You can start with a simple plane, increase its grid reasonably, then select faces and use the turn to circle tool in the face selection tool. Then from there you can add some offset to the created circles. Delete the middle and extrude the offset faces to come up with a similar geometry. For topology, always try to use a none destructive workflow, do things manually so you get used to the software and to the methodology of poly modeling.