I have a question regarding getting a SIM card for an iPhone 5.

Verizon has assured me that the phone is already unlocked and I was thinking of getting a Pay As You Go SIM when I arrive at Heathrow.

Does anyone know if you need to sync the phone to iTunes in order for the SIM/phone to activate/work? I won't be bringing my computer with me and I'll be pressed for time, so if I need to actually connect to iTunes to make it work, I'll just have to use Verizons Global plan.

Any info would be great, thanks.