Quickest way to get settings is connect to the internet via wifi on your phone and download the Giffgaff app from the App Store. From here you can automatically install the APN settings without having to manually sit and type them out! Good luck !
step by step settings to get MMS and the internet on an iphone
Step 1: Firstly, check whether you have an old profile. Head to Settings > General > Profile. If you can't see "Profile" move on to step 2. If you can see an old giffgaff profile, tap it and press "Remove".
Step 2: Go back to Settings > General and press "Reset". Don't worry, this doesn't delete any of your personal belongings.
Step 3: Hit "Reset Network Settings" and follow through. Note that this will delete your WiFi passwords! You may need to enter your passcode, at which point your iPhone will reboot.
Step 4: Go back to Settings > General > "Mobile Data" or "Network" (depending on your iOS version).
Step 5: Tap "Mobile Data Network". Now under "Mobile Data" enter:
APN - giffgaff.com
Username - vertigo
Password - password (this should already be entered by default)
Leave Visual Voicemail as it is.
Step 6 (Almost there): Scroll down. Under MMS enter:
APN – giffgaff.com
Username – vertigo
Password – password (again, this is the default)
MMS Proxy: 126.96.36.199:8080
MMS Max Message Size - 2097152
MMS UA Prof URL (just leave blank)
Do NOT press the " Reset Settings " button when you’ve done this.
Once the settings are put in, turn your iphone fully OFF and then back ON again.
Then, press “ Settings “…“ Messages “ and ensure that " MMS Messaging " button is set to ON.
Press Settings, then General, then Mobile Data to ensure that the " Enable 3G " button and the " Mobile Data " button are set to ON.
Go to " Settings " ... " Carrier " and change to O2-UK.