I assumed it works just like any tethering system... you can see on RedMist's video, it says when you boot up:
"Welcome to HP mobile hotspot
You need a special data feature from your carrier in order to use HP mobile hotspot. While mobile hotspot is active, on-device features will continue to work and will use the mobile hotspot data feature allowance"
Now I know its all complicated plans and carrier sub-apps in the US, but in the UK, it just comes under 'tethering charge' as I understand it.
With O2, I have free tethering, so will it just work for me?