Hello UK30000,
The wifi that is built into your laptop will most likely be a 802.11B or 802.11G network adapter. So basically to utilize that, you have to go to wifi hotspots that use the same protocol. If they have those hotspots in public places, there shouldn't be any charge for the service unless it's like an internet cafe and they have their hotspot password protected before you can use it. If you know it is a public hotspot (like in an airport) that uses 802.11 wireless routers to share internet access and you can't get the internet to work, it is most likely due to incorrect settings in your laptop.
Now if you are talking about getting internet anywhere you travel, for example, on highways, you will need to sign up with a service (typically through a cell phone company) and get an additional adapter that sends/receives those signals. The price for that type of internet will just vary on the internet service provider you choose.
I am not sure what is available in the UK, but in the US, I know Verizon and Cingular both have internet anywhere services for around 50-80 dollars per month.
Hope that info helps you!
