GiffGaff Nano sim cards which has £5 free credit when you activate it online!!

Great network, runs off o2 so brilliant coverage. CHEAP!!

Have lots of "Goody Bags" to choose from - prepaid bundles of mins/texts/mobile web.

Has a great on-line forum.

Can keep your number if you choose to.

The sim will be cut down from a full size sim card using a pprofessional cutter.