Thanks Eliot,
I see that it's there, but the customer wants just a single Facebook share icon as he thinks people wont know to click the plus and it's in keeping with the layout 
I did enter the code manually for the share button, but the site url gets placed in front of the facebook share url for some reason.
If I wanted to manually add the code how would I avoid the reverse url?
The other problem with the send is it doesn't allow you to change the thumbnail, and for my products shows the wrong thumbnail.
Many Thanks
Ian