Your Superdrug Mobile SIM may not work abroad unless you make a one-off change to your phone settings. Here's a short video that shows how to change your settings.
Follow these steps to get your phone ready:
Go to ‘Settings’
Open ‘Mobile Data’
Open ‘Mobile Data Network’
Change the Mobile Data APN to: superdrug.net
That’s the only thing you have to change. If there’s any information in other fields, you can leave it as it is. It should look like this: