Do I need a personal or business account?
Personal accounts are ideal unless you are a VAT registered business. Businesses accounts are used to allow the shop software calculate and display VAT correctly. If you are a business with a VAT number, you'll need a business account in the shop and you'll also need to add your registered VAT number to your account in order for VAT calculations to be processed correctly.
If you already have an account you can edit the type of account from personal to business in your Account Information. You can also amend your address, and update or add a VAT number in your Address Book.