Once you join giffgaff you'll get:
Get 2GB data for only £10 a month. Plus 500 UK minutes and unlimited texts.
More info on prices
If you're an iPhone 4 or iPhone 4S user you will need a Micro SIM in order to join giffgaff. The same applies for new Nokia phones such as the Lumia 800 and Lumia 710 and the iPad.