Free
GiffGaff sim card with 5 pound free credit.
Once you activate these sims you will receive 5 pound free credit.
So for example:- you top up £10 you will actually get £15 for the price of £10.
Giffgaff runs on the o2 network, so you dont even have to unlock your phone if you have an o2 handset.
If you have an unlocked handset these sim cards work fine.
Calls per min UK landlines and mobiles 10p
Texts 6p
0800 Free
Or buy a Goody Bag starting from £5