So this deal is on O2 Refresh which I have used a few times before to get phones cheapish. Take n out the phone contract and paid it off after the first month or so (not sure of time frame but i've done it after one month), no additional costs and no need to pay for the remaining line rental.
If you are interested take a look. The phone cost is for the £33pm and £9.99 upfront costs with a phone credit of £360 to pay, others are priced at £480 for the total phone cost.
The direct link can be found here for the green one. https://www.o2.co.uk/shop/refreshTariffs/nokia/lumia-930-green/
Possible £55 quidco too (not put in title as you will need to keep the contract for it to approve) http://www.quidco.com/o2-mobiles/rp-04/?ac
Also if you are planning on keeping the contract O2 do a variety of 30% airtime discount pm. I got mine via NUS, girlfriend from the company she worked for. I'm not sure how to do it any other way but this site should give you an idea. You visit o2open.co.uk but read the link below first. http://forums.moneysavingexpert.com/showthread.php?t=3934271