How should I best prepare for my GCSE Italian Oral?

The most important thing to do is to practise. Practise speaking in Italian to a native Italian speaker if possible, if not friend, your Mum, your mirror are all also useful. Websites like duolinguo allow you to practise your language skills and they provide speaking tests as well. On top of this, if you know the possible topics that may come up in the exam, it may be useful to practise talking about these topics, as well as writing about them and learning important vocabulary that you may want to use related to these topics. Finally, just make sure to immerse yourself, so your head is fully in 'Italian mode' before the exam. You could do this by watching Italian youtube videos, or listening to a podcast or music in Italian, or watching an Italian film before you go to bed. And finally, relax. You will be great!