Thanks guys. Like some of you, whilst I'm not "tied"to Apple products, in our household we have 2 Iphones, 3 ipads and a Macbook Air, so I've kinda become a Apple person without realising it

Work have now agreed to pay for unlocking of my 4s, so I'll give that a go as well. in the meantime, I've discovered the phone they will give me whilst my unlock code comes through (which could apparently take up to a month), is a Nokia Lumia 520. Not bad, but not sure I'd get on with this long term.
As regards Vodafone to Orange, well I don't get a choice. The company I work for worldwide has over 22,000 mobile phones, and over a 1000 in the UK alone though our various companies, so I can see how a little financial incentive from another provider can has a massive effect on our UK bills. Coupled to that, we always had pretty poor coverage from Vodafone (signal strength wise) in our area, so I guess that's another incentive. We've been with Vodafone now for 11 years so it's a big deal for us to change and I guess Orange made us an offer we couldn't refuse. Nothing I can do about that. Let's just hope they work out or next year we could be back on Vodafone !