Hi there
Which template mode (Classic, Paired, or Native) are you using? You could also quickly share the URL to your site here so we can have a quick look.
In the Classic mode there currently is no checkbox solution to add a menu, so it would indeed require some custom coding to override the template.
It’s something we might make easier in the future, but at the moment there are no immediate plans to do so.
Right now, the easiest way is to switch to Paired or Native mode instead. You can then use your normal theme in AMP, and the menus and widgets that are shown in your normal theme’s templates. You can do this using the Twenty Fifteen through Twenty Nineteen core themes which have been tested. Other themes should work as well, but some functionality won’t work without some adjustments (in particular, themes that depend on custom JavaScript).
