What phone contract shall i get ?!?!?

I want a LG KS360 in any colour or a Nokia 5310 in pink. I want it to be on a contract though. I have looked at all the phone companys (Orange,T-mobile,Virgin,O2,3 and Tesco) But i havent found a good one yet. I want it to be no longer that 18 months (12 months prefrably) and at a maximum of �20 per month. Pleeease help me :) x