Thanks @cole for the answer
We are going the "administrator" route to stop people publishing to production (but allowing them to publish to staging) - so following your advice.
But it would definitely be useful for us to be able to refuse direct publishing too though so please do add it to the product request list.
Another thing in a similar vein would be having some ,gcfg way to configure the header and site title.
Currently I've got some hacking going using:
LoggedInWarning = "This is the UAT RStudio Connect Instance <style type='text/css'> #rStudioHeader .band { background-color: pink; } #rStudioHeader .productLogo:before { content: 'UAT'; } #rStudioHeader .productLogo { text-align: right; font-size: smaller; } </style>"
But this only works on the main landing page and isn't particularly pretty...

Really I would like some way to customise the header and title universally and with slightly less obscure css 