There are decent internet cafe-style terminals dotted around, if you know where to look. In the South Terminal, on the Village floor, between a Costa Coffee and MacDonalds I found a cluster of about 12 desks. No one around. Fees were in increments of 50p with some sites free. Maybe not perfect for doing business but if you're just checking webmail then it's fine. Couldn't really complain about the mobile signal (GPRS over my old Nokia). Was OK though in the middle of the terminal I was concerned I was losing some rececption.