I recently made the switch from EE to Sky Mobile
and immediately ran into an issue on my iPhone tethering my laptop using Personal Hotspot. I tried to reset the network settings and checked everything I could think of to get tethering via Personal Hotspot working.
In the end the fix turned out to be quite easy. Simply go to Settings->Cellular->Cellular Data Options->Cellular Data Network and then scroll down to Personal Hotspot and set the APN to ‘mobile.sky‘ and you’re all set.