How to do line breaks like the More and Next Page

When I am adding images and floating left or right I usually want the next paragraph to appear after that thumbnail. I clicked the “More..” and “Next Page” entries and in the editor it looked how I wanted, but I understand these have a different purpose and usage. The only “solution” I have is to edit the HTML, but this defeats the purpose of the live editor. Are there any plugins that do this? I have tried the Advanced TinyMCE but the toolbar didn’t appear for me. All I want is a simple way to stop images from stacking when floated.