Juliespence, have you checked is MMS is on under Messaging?
If so, please try this (it may be asking you to repeat what you have already done, but its worked for a few people).
What you need to do is go into Settings, General, Network, Cellular Data Network, scroll down to the bottom of the page and do Reset Settings. Once done, input the settings again: Cellular Data - APN giffgaff.com, Username giffgaff, leave password the same. After that go straight to MMS, do exactly the same, APN giffgaff.com , Username giffgaff . Once done, press Network on the top left of the screen. Then press the Home Button. Then do a Hard Reset - Hold home button and on/off button together until the phone switches off and let go of the buttons once the Apple logo appears. Hopefully this should work for you.