I appreciate debugging can be difficult like this, and I appreciate any help you can give me. For the points you made:

1. Closed everything down and opened Word again, and went back into the QA Toolbar. It only shows the module once now (on each side) and it's the 'Normal.module' one.
2. The template is stored in folder containing other templates (none of them have macros). It's accessed by clicking on 'File' and 'New'
3. Macro settings are 'Enabled'
4. I can't add the location to the Trusted Locations list. Looks like an Organisational setting that prevents it.

Will the lack of Trusted Location be potentially what's stopping it? If so, why does it work in the template, but not in new documents?