Thanks but google still says it can't verify the site. Unless it's just a case of waiting?
I have looked on Google's help page and it has information about what to do if you get the error message I get - I just don't understand how to do it.
Your site doesn't return a 4xx HTML status code for non-existing URLs
If you're using HTML verification, it's important that a non-existing URL returns a 4xx status code. We can't verify sites configured to return other status codes (such as 2xx or 5xx) for non-existing URLs, because this would enable anyone to verify ownership of your site. You can try our meta tag verification method or change your server's configuration.
This configuration presents a security risk for site verification and therefore, we can't verify your site. If your web server is configured to return a status of 200 (found) in the header of 404 (not found) pages, and we enabled you to verify your site with this configuration, others would be able to take advantage of this and verify your site as well. To ensure that no one can take advantage of this configuration to view statistics to sites they don't own, we only verify sites that return a status of 404 in the header of 404 pages.
If your server is configured to return something other than a 404 for non-existent pages, try our meta tag verification method or change your server's configuration.
You can change your web server configuration to return a status of 404 in the header of 404 pages and still provide a custom error page (see Apache information and IIS information). Once your web server is configured correctly, try to verify the site again and we'll recheck your configuration.