Thanks but I already use Ctrl+Shift+Space to do this manually but I won't usually know when this is going to be a problem and I don't want to have to try to form the habit of doing this every single time I write a unit. If I change the margins of the document or make a change to a sentence or paragraph then what was once fine may then require a non-breaking space.

Would it be possible to autocorrect every space before min, hr, sec, g, kg, l, ml, μl etc into a non-breaking space? I only ever use those units when they are preceded by numerical digits.