Next/Previous page not working on custom page

I’ve adapted/built a custom page template which is running fine, all apart from that when you click on the ‘older entries’ link, it displays the same 12 posts. I’ve crawled the forums here and there are many similar questions with responses, but I can’t get any of them to work, and so here is the code from the page in question below, if someone can have a look!

Thanks!

[Code moderated as per the Forum Rules. Please use the pastebin]