Dawn theme - how do I add 'country' field to email signup block?

I want to know which country customers are from who are signing up on my pre-launch ‘password’ landing page. Currently the only field available to them is email using the email form block. I could also use the contact form block if this is easier but it also has no country field for them to select where they’re from.

The strange thing is that when customer’s sign up with their email, the account that’s created for them has ‘country’ in their information but this is just sitting as UK default currently.

Thanks for any help.