Same sex wedding in England - visas?

Hi, I am a British citizen and my partner is Australian. We are travelling to England next month to register the wedding, which we plan to have in England in January Protected content . As my partner is divorced we knew it may take a while for the registration to be confirmed.
I have been reading about it and it seems my partner may need a marriage visa in order to register the wedding but it seems to indicate that you remain in England, get married within 6 months and then leave. We will not be getting married for 8 months after we leave England in May, so do we need a visa in order to register the wedding, or only we return for the wedding itself, or do we need a visa for both occasions?
Confused!!!!!
Thanks
Lee