Voting is open, page-55

That's correct. You would need to register yourself with Computershare to access/view your holdings on the Computershare registry which TNG subscribes to.
Having said that, there is a link in the email sent on 09-Aug-2022 regarding the Notice of Meeting that when clicked, should take you to your voting preferences. You would need to enter your postcode when asked for it.
If you are not able to use this link, it would most likely be due to the fact that you have not registered yourself as a ComputerShare login/user which is quite straight forward.