Which is the best UK mobile phone carrier?

I'm moving to England for a while later in the year (I'm Australian) and was wondering which mobile phone carrier is generally the one to go with which has the following features: International text messaging (so I can text Australia regularly) and will also have international roaming for when I go to... show more I'm moving to England for a while later in the year (I'm Australian) and was wondering which mobile phone carrier is generally the one to go with which has the following features:
International text messaging (so I can text Australia regularly) and will also have international roaming for when I go to Europe etc.

I had thought maybe Vodafone but couldn't seem to find anyting about being able to send international texts on their site. Also, when I was there in 2006, I bought I cheap vodafone mobile with a pre-paid sim and it didn't send international texts.

I'd probably rather pre-paid. Or pay as you go as I think it's called.

Thanks for any help!
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