The question you may be asking yourself is can I get the Apple iPhone if I have bad credit history? The answer is not a simple one, sure you can try your best to get it but remember it is a £400-500 handset and one of the first pieces of advice when applying for a mobile phone with bad credit is opt for a mid range handset.
The iPhone is a nifty bit of kit but there are several lower end handsets that have nearly all the same functions which are cheaper and therefore have a better approval rate. The iPhone has stricter conditions than many handsets and you may struggle to get one if you have severe bad credit, however if you just have no credit history it may be worth a try as you have to start somewhere.
Alternatively apply for a sim only contract with 3 Mobile or Vodafone and get the iPhone in a few months once you have built up some loyalty.