Thank you for the replies.
Can I just check, please, that what I want to do is classed as tethering?
After much deliberation, I have recently bought a Microsoft Lumia 550 running Windows 10 Mobile on O2 PAYG.
My old Nokia phone has a GiffGaff SIM and I need to decided whether to stay with GiffGaff or move to O2. I am assuming that the O2 Lumia phone will accept the GiffGaff SIM.
The Lumia 550 / Windows 10 Mobile has a feature to create a Wi-Fi hotspot (which is connected to the 4G data on the SIM) which I would like to use with my iPod Touch for light use, as the iPod has a number of apps that are not available on Windows Mobile.
Is using the Wi-Fi hotspot feature considered tethering?
Thanks again.