For those that may have problems with this and it could be for MacBook or other devices but when I connected my MacBook to O2 wifi it connected but wouldn't go to the welcome page...
What you need to do is... Click on the WiFi tab and open network preferences> by status it will give you the IP address copy this> open up internet browser and paste> this will take you to the welcome page so that you can register your device.
Hope that helps