Thanks Nikko,

Unfortunately my issue is that I cannot even see the tab to change to the visual editor from the text editor so I cannot see the full array of options.
That being said, I found someone having this issue on another thread and it was solved by creating a new administrator account, which has also worked for me. So long story short this is now solved, however I still don’t know why it was happening.

Thanks for your help anyway, much appreciated.