@thatwastaxing Sorry, I decided not to incorporate the not-so-perfect solution I found for this as there is a perfectly capable option within WP already which accommodates us (which I didn't realise well enough before).
I intend the below to be included in the FAQ of the next version of the plugin.
= Why are the notes only shown on the plugins page and not on the update page ? That would be super-useful! =
There is no hook available to hook into on the update page, however, you can easily still see an overview of only the plugins which need updates with their notes.
By default, the plugins page will open to the All view. At the top of the page you can however choose the following alternative views: Active | Inactive | Update available. The plugin notes *will* display in those alternative views.
From the Update available view (and from any other plugin page view for that matter), you can then check the checkbox for any number of the plugins which you want to update and choose the Update option from the drop-down list at the top and bottom of the list to start updating.
Hope this helps. Will this suffice as a solution for you ?