Hi Paddy,
Thank you for your feedback.
From your screenshot, I understand that you’re using the Office 365 Preview. I would like to explain that the Office 365 Preview cannot be purchased as paid subscription at present. It is recommended you sign up a new free trial Office 365 account which can be purchased by referring to the link in my last post.
Here is another link for your reference: Select an Office 365 plan for business. You may click Buy now or Free trial at the bottom of the plan you would like to use.
Your understanding is highly appreciated.
Best Regards,
Allen Zhang