You can use the WiFi hotspots in McD's, many pubs/restaurants, motorway services or coffee shops for e.g.
As this is in the 'mobile world' forum, do you intend to use your phone as a modem? If so, what model phone do you have?
I have used a HTC Tytn 2 windows based phone to access the net via 3G and got a respectable 1Mb connection. In this case I just connect the phone's mini USB to the laptops's USB and set the connection to 'USB' on the network page of the phone.