On many of the new Vodafone tariffs you get 500MB of mobile Internet and email allowance a month bundled in for free (usable 24/7 not just off-peak). I use my Nokia N95 8GB for checking out the Internet and the speeds are perfectly usable.
If you get something like the
Samsung F-700 you'll even get a full QWERTY keyboard and a portrait aspect screen (you can also use it as a camera and.... ohhh yeah, a phone)
