I set my account up as an individual, can I now change this to a business account?

Yes, this is done very simply. When logged into Bookvault, navigate to the 'payments' section.

On the righthand side of the page, you'll see an option to 'Switch to Business':

The system will then prompt you for your company name and VAT number, if you don't currently have a VAT number you can input 000000 for the time being.

And then you're all done and your account has been switched over.