Sorry, this is not practical. Autocorrect would treat the following as individual cases:
7
17
27


117
Each would require its own AutoCorrect entry.
In addition, the space is a trigger character and you can't include it at the end of the entry.
If, instead, you just had the numbers, you would end up adding the nonbreaking space before a period or comma as well, since those are also triggers.

Are you aware that Ctrl+Shift+Space = nonbreaking space?

Automated Boilerplate Using Microsoft Word

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.