3 hours ago, lordignus said:Inspecting the page source, something goes wrong while it's trying to load the email notifier from ps_mailalerts.
Try disabling the module option to allow customers to get notifications, and see if that works.
If that fixes it, take a look at whatever is hooked in displayGDPRConsent because that's the hook that's called on the next line after the email input box where the page crashes.
Hope that gives you something to run with 🙂
Disabling the mail alerts module has indeed solved the issue
I then reset the module and it stopped loading out of stock products again. I went into the module settings and removed notifications for out of stock products for customers and admin and that seems to have sorted it now 
Thanks for your assistance