Or alternatively, save your money and enjoy the clover. Clover fixes
nitrogen and in an organic lawn is a good companion for grass. I'm actively
encouraging clover to spread and my daughters (and the local birdlife) like
the little white flowers (OK, so I don't mow that often either ;-) ).

I never have managed to get any red clover to establish though. If anyone
has any tips, drop me a line.

Paul DS.