you obviously have the internet....take 5 minutes and look
What part of "I've done some searches on it, but I've been left very confused!" don't you get?
@Chris123: Thanks for your insight. I've only been looking at Galaxy S3 LTE, but I think I'll include the S4 too and compare the price difference.
@TheDr: Thank you for your helpful and informative reply. I wanted one on contract as I was advised this is more cost effective, especially since phones can develop a fault. And you don't have to sell your old phone if you want to upgrade.
But I've struggled to find the LTE version of Samsung S3 i9305, and because this will be my first smartphone, I'm flummoxed by some of the jargon and networks, etc. That's why I asked for advice, it's a big decision and I want to make a good choice.
Oh well, back to searching! Thanks again you two!