Thank you for the replies.
wco81-
I have a UK PAYG phone that I will use for my phone calls so I don't need to worry about an International plan for my iphone. Thank you for the info, though.
Will I be able to use "location services" with only WiFi and "airplane mode" enabled on my iphone 3gs? I want to be able to use my London A-Z app, if possible, which needs location services to be enabled for some of it's features?