HTC WILDFIRE ON PAY&GO FOR O2? TEXTS/INTERNET?

I'm looking to purchase the HTC Wildfire, but hope to remain on a Pay&Go service from o2. I'm currently on simplicity, in which i top-up �10, �5 of which gets taken off a month for unlimited texts. Can any one tell me or suggest which tariff would be the best from o2, in which i can have unlimited texts and a reasonable amount of data allowance for the same if not similar price, if possible. Any answers would be much appreciated. Thanks! =]