With the launch of 4G there are a few new things, so here are the few most important things for you to be aware of. This is all included in the KB articles and quizzes, but I thought it would be useful to call out the key things here.
All the best,
Another important note for those with slightly older phones: the iPhone 5 (and earlier iPhones) will not work on giffgaff 4G. They cannot be "unlocked" or "enabled" — there is no way to do it, and anyone who says there is is wrong.
As far as UK networks are concerned, the iPhone 5 is 4G compatible on EE and 3 (and on MVNOs that use either of these networks) only. This is because Apple did not incorporate the technology necessary for other networks.