I updated my iPhone 4s and now it will only connect to the internet at home?

It happened before and the apple shop guy fixed it but i can't be bothered to drive all the way to the apple shop to have it fixed.anyone know what i can do to fix it? I think it's something to do with the carrier (giffgaff)- but i'm not sure. Any helpful answers will be greatly appreciated.

Have you checked the settings
-> Data enabled - Yes?
-> 3G enabled - Yes?

you can also ask GiffGaff to re-send the network settings to phone, in case they were lost during the upgrade - they should have been restored by iTunes after the upgrade (did you back up and restore?)

fgaff.com/t5/Unlocking-Discussions-Knowledge/Guide-to-using-an-iPhone-on-giffgaff/ta-p/3522027 - getting an iPhone working on GiffGaff

that will show how to set them manually also.
fgaff.com/t5/Learn-giffgaff-Top-Tips/The-giffgaff-Internet-Settings-Guide-Setup/td-p/2066679