URLs, gallery-template.php & gallery-single-template.php

I have lots of galleries setup that use the template :

gallery-single-template.php

the permalinks are turned off so they can be accessed at (for example) :

https://213.175.214.220/~wwwmattb/?gallery=lode-stones

https://213.175.214.220/~wwwmattb/?gallery=new-luce

However I want to access the parent galleries (if thats the right word) which should list thumbnail links to the child galleries (lode stones & new luce). This should use the other template :

gallery-template.php

But what url do I use to access this?

thanks in advance

https://www.ads-software.com/extend/plugins/gallery-plugin/