Posted: 16/03/2013 at 17:00
Rich, this may sound extreme but...
You could consider starting off from scratch and ripping the whole thing out. By that I mean strip off the lawn, dig out some of the clay, add drainage and then dump a load of new top soil ontop. This could be heavy work and may need a mini digger and a couple of skips. And would require you to be on the lookout for someone wanting rid of their top soil. But then you would be starting from the beginning with a good usable garden for the future.
If your garden is bad now, then chances are future plants might not thrive and in years to come you may end up digging it all out anyway. Obviously Ive not seen your garden and you may not need to go to such measures. Perhaps you could just dig out the clay soil in your borders and leave the rest? But I guess the lawn wont thank you in the future.
Any chance of a photo showing the whole garden?