I've been thinking about 02 Simplicity tariffs. Online 10 - £9.79 per month for 150 mins and 300 texts.

It's a 30 day rolling contract too so you're not tied in if/when phone breaks. I'd check more carefully for web browsing though - it isn't something I use. I THINK o2 give you 1MB allowance, then charge after that, but not sure what charge is.

(btw - this is personal opinion. I've been with 02 for years and had no probs - I found this deal looking for myself. I'm not an expert on this stuff, and I haven't looked into many other suppliers.)