Ben, I've used Warranty Direct and been pleased with them. They are not the usual cowboys, nor do they only cover things that never fail, like crankshafts and gearbox casings!
They quoted me £300 for a years 'extra cover' on my C-Max, and you can defer it by 3 months until the Ford guarantee runs out. WD cover wear and tear too, after 90 days, which many do not. You can adjust the premium by choosing main dealers or independents. It was a bit less because I have my SLK covered by them too.
I have no connection other than a satisfied user. That said, if you don't already have breakdown cover, then the Ford one looks fair value.
2008 model 1.8 petrol C-Max Zetec in Avalon Blue - arrived 14 May 2011. Also own and drive: 2005 Mercedes Benz SLK350 and wife\'s Fiat Panda 1.2 skydome.