At the moment, you'll only know of issues once they're in prod.
When a tag is created, that becomes production.
Add the build archive to the GitHub release.
Take care not to tag anything that isn't stable!
qa.<domain>.s3-website-eu-west-1.amazonaws.com tracks the qa branch.
When it is pushed to, create/update the bucket.
You can commit to master all day long, merge things in etc. without incurring fees. When you're ready to test it out, push to QA. If it's then good, tag it. It is envisaged that all tags will be created from the QA branch.
At the moment, you'll only know of issues once they're in prod.
qa.<domain>.s3-website-eu-west-1.amazonaws.comtracks theqabranch.