After spending some time fiddling with the Public face site, Michael and I have found that customizing the site beyond what Microsoft has provided is rather difficult and headache inducing.
I stick by what I said about editing the .ASPX files, it is very easy adding new content in HTML using Sharepoint Designer, however, it’s the master page that is proving to be the big problem. We wanted to edit the structure of the website, change the navigation and the shape of the site completely, this isn’t covered in Office 365 ‘Out-0f-the-box’ tools, so the sites master page needs to be edited. This is a problem, Microsoft does not allow you to edit the master page provided and leaves the user stuck with what they give you, the phrase “You’ll get nothing and like it!” springs to mind.
One user claims to have a workaround for this, copying and editing a masterpage outside of Sharepoint, reinserting it into the correct folder and editing the .ASPX files to accept the new master page. I’ll report back once I have tested this.