I like to keep things as simple as possible & bought a Tesco Value Mobile SIM.
The special offer of the card plus £10 airtime for £5 looks ok, atm
http://www.tescophones.com/sim-only/
As said it will only do talk & text & is UK only, but 5p per text & 15p a minute calls are to all networks at all times.
The main disadvantage on this tariff is that you are tied to topping up via Tesco, but it can be done online or by phone with a credit or debit card.