How to clean copper?  

a resource
garlanre,
Take a look at the "find a conservator" drop down at the The American Institute for Conservation of Historic and Artistic Works (AIC) site.
I hope you are not surprised at the cost of a professional conservator. They do not seem to work on every street corner. My wife and sister both damaged their Swaine Adeney Brigg women's umbrellas (yes there is a difference in size and shape) and best service is in London. The decoy was already in my collection and not purchased for future restoration.
Since I am willing to accept the cost of professional restoration I am never able to accept less than the best. I am not a "picky" customer, but I am certainly a "particular and demanding" client. Your table can look new again for a cost.
http://www.conservation-us.org/

intaglio
Since it is intaglio, it might not be so horribly risky and expensive to try and restore it. I have seen copper "printed" with patina and then finished over so the patina does not continue, and this is what I thought the table is. And this is what I absolutely wouldn't want to deal with.
It is still a significant undertaking very suitable for an professional, as the contrast appears to have been increased by patinating (probably it is a copper oxide patina) the etched areas. A professional could "restore" that if some were lost in removing verdigris and other age acquired chemical compound patina.