I tried the follow me with a cross section before i posted - couldn't get it to work. However, I have cracked it! I constructed a doughnut with follow me and isolated a thin section from its centre with an extruded circle and then intersected the two faces and deleted the outer bulk of the doughnut. Phew. I'm off to try your method again.

It sounds to me as if you either have the circle drawn outside a group or component. If so, the Push/Pull tool will extrude a cylinder but it won't create a hole because the plate, being in a group/component is protected from being modified. Delete the circle, open the plate g/c for editing and then draw the circle and push it through.

I believe what you may want is ThomThom's Edge Tools. At the top of this page see the red button to the Plugins Index. Look for the set under ThomThom, click on the name and the topic will come up. The first post explains, describes the usage. I believe this is a free one. "Vertex Tools" however, I believe is commercial.

The plugin Fillet Tool does exactly what you want. http://rhin.crai.archi.fr/rld/plugin_details.php?id=146