The mobile phone deals are basically of 3 types. Contract deals, pay as you go deals and sim free deals. People who don't have large phone budgets generally opt for Pay As You Go Phones. These phones provide a person full liberty of filling in his phone balance as per his requirement.
Samsung, Sony Ericsson, Nokia, LG, HTC, Blackberry, Acer etc. name any brand, Payg Mobile Phones are available on any make of phone. PAYG deals can be taken up on that network which you feel is best for you. Orange, O2, 3, T mobile, Virgin and Vodafone are to name a few of the leading wireless network providers of UK. You can choose any one that satisfies you. The best thing about pay as you go deals is that one can easily change the networks in case he or she is not satisfied with the current network provider.