Hi there @happytwit
Your giffgaff phone " settings " should actually be automatically installed once you put your giffgaff sim card into your device, so please make sure that your mobile Data is turned ON of course.
If you would like to install your "settings " manually, that's really easy.
Go to your device "settings"
Select "More "settings"
Select "Wireless and networks".
Select "Mobile networks".
Select "Access point names".
Now tap the menu key.
Select new APN.
( Type in this information below ).
Password - ( leave blank )
MMS proxy 220.127.116.11
Authentication type -PAP
APN type - default,supl,mms
Press the menu key,then select SAVE APN.
Now Tick the little circle next to the APN,and you'll see the green light.
Now simply Turn your device OFF and On again ,and Also make sure that your "mobile data" is Enabled or Packet Data, in your "Mobile and Wireless Network " Settings ".