That's exactly why I use Autoaid http://www.autoaidbreakdown.co.uk/index.htm it's £36 / annum, you pay for the cost of the breakdown yourself by cash or card, get a receipt... then claim it back within Ten days (it works as well). It covers callout at home up to £65 with unlimited help away from home, also cover for your legal spouse is free....so in effect I cover 2 seperate cars for the bargain price of £36. !
Not trying to sell it, but it knocks spots off most other conventional breakdown cover schemes.