Use code: FB12

(Sorry for long post but worth a read - please scroll down to read entire post - couple of deals)
Add £10 worth of credit to your People's Operator sim card via their website and use the code included in the deal and you'll receive an additional £30 worth of free credit.
Just use the code at the People's Operator checkout and you'll get the free credit applied to your account.

Another TPO deal:
One Month Free Unlimited Mobile Phone Contract (Unlimited Texts, Minutes & Data

Select the £14.99 - then use code: TPOFREE Included in the deal when signing up for the £14.99 per month unlimited contract from The People's Operator, which includes unlimited text messages, unlimited minutes and unlimited mobile data and you'll get the second month of your contract for free.

The contract is normally priced at £14.99 per month and already one of the cheapest unlimited sims around. It lasts for a minimum of 30 days, plus you can choose to have 10% of your monthly bill donated to a charity of your choice, at no extra cost. Complete the order form as required to request your sim card and get your second month free.