Hi - I want to reset my security questions but the email address assigned to this is incorrect - can this be changed to my primary email address please?

No, you won't be able to change your rescue email address until you can answer your questions, and you won't be able to set it to be the same as any other email address on the account. You will have to contact Support in your country to get the questions reset.

Contacting Apple about account security : Contact Apple for help with Apple ID account security

If your country isn't on that page then try this form and explain and see what they reply with : https://ssl.apple.com/emea/support/itunes/contact.html

When they've been reset you can update your rescue email address for potential future use : Manage your Apple ID primary, rescue, alternate, and notification email addresses

Or if it's available in your country you could change to 2-step verification : Frequently asked questions about two-step verification for Apple ID