Does anyone know if these sims will work? http://freesim.o2.co.uk/sKTLPi92
I doubt it, they tend to be configured differently as they only transmit data.
So getting a call/text allowance sorted on an iPad SIM would be a pain in the arse and O2 would likely refuse it.
Look at the general deals you would get on other smartphones in terms of monthly cost and the amount of stuff you get included.
Then look at the iphone, to get the same amount of minutes/texts/data you will be paying more. What's even more amusing is that the actual hardware (just a PAYG jobby without contract) costs about the same for a brand new top of the range android as it does for a brand new iPhone. Apple tax. It's awesome.
iPhone contracts are generally very expensive, but Apple's customer service is far better than any Android phone manufacturer will give you and the resale value will be considerably higher.