or jailbreak and unlock...
If you put the iPhone on a Vodaphone pay monthly plan you could then request the unlock as well
You could try their online unlocking form http://campaigns.vodafone.co.uk/UnlockCodeRequestForm/
There were reports in the past of people getting their iphones unlocked via this method even with incorrect details.
From what my cousin in Slough told me he haveto be on for a month but alas he got it unlocked Ive never heard of only the original owner being able to request an unlockWould he be able to do it straight away? I think here in Ireland you have to be on a pay monthly plan for 6 months then they'll unlock it for you.