I double-space after a full stop what ever the font is that I'm using. But when I was an editor, all those years ago before I had my children, I would replace two spaces with one before sending a mss off to the designer.
Having said all of that, I don't think that this is one of those issues that an editor will reject you over. Using a fancy font, printing on pretty flowery paper, and decorating your work with slices of fruit, yes--but two spaces after a stop? No.