I have several items in one region of the header and footer, say:

Item1 Item2 Item3

all in the bottom left of a page.

Now I want to space these apart. Prince seems to be treating whitespace like HTML (in that it condenses it so I can't put in " ") but non breaking spaces are coming out as " "

So, how do I put some space between my items?

You can add non-breaking spaces with \A0 escapes in CSS, or specify "white-space: pre" to prevent white-space collapsing.