Voice will automatically create a certificate for your site after it has validated the domain. You don't need to add your own certificates.
However, curently for your domain the validation is failing because you have an IPv6 record (AAAA) pointing to the wrong place. Currently voice does not have an IPv6 address, only IPv4.
So if you delete this AAAA record from your DNS (leaving the A records for your site pointing to 184.108.40.206), then after a few minutes the system will be able to validate your domain and will automatically install an SSL certificate.
Once this is done then when you log into your site you will automatically be redirected to the https version.
That's great thank you. The IPv6 record must have been left over from the last 're-direct' and I only changed the A record. AAAA records cleaned up now so hopefully should be sorted shortly.
Thank you so much for your help, it's been doing my head in for the last couple of days!
And indeed - it now seems to have validated and installed a certificate! :-)