I think you may find that voids and whether payment is due are up to the discretion of the relevant local authority.
In my case I was unable to even get the single person discount during covid after my tenants left (as I foolishly told them it was unfurnished) and, even worse, if it had remained empty for more than a year 2years I would have had to then pay double.......
In comparison a quick look online shows Glasgow offer up to 6 months "free" if tenants have left and the place is empty.