Two things that might work: they are under Properties in the Layout tab in Table Tools, which should show up in the ribbon if you select the table.

If you don't need text to wrap around the table, choose None under Text Wrapping. This should make the table behave like an inline graphic, part of a paragraph, and you can set space above and so on.

If you do need text to wrap around the table, when you choose Around under Text Wrapping, the Positioning button should no longer be grayed out. You can use it to set the position of the table relative to the page, the margin, etc.