There's not going to be a definitive answer to this, I'm afraid. Payment by phone is relatively new and the security standards weren't in place when most current models were being designed. NFC was included mainly for device connection and, although using it for payment may have been hinted at, no one really knew the process.
The situation as it now is is this:
1. Your device needs to be certified as being compatible with the Vodafone system.
2. It also needs to be running Vodafone software. If you got the phone on contract, that'll be fine. It you brought it from another network, or bought it SIM-free, it won't.
3. Your account needs to be on the new billing system, which is being rolled out in stages and works with the SIM.
When all that's in place, you should be sent an NFC SIM (at least, I think they'll be pushed). This doesn't as its name implies, do the NFC stuff, it just contains the security module that works with your phone's NFC.
There used to be a list of approved devices, but I can't find it at the moment.
