Posted: 23/02/2014 at 07:50
I'm no expert, but I'm sure raising the soil above neighbouring areas would help with drainage. The main way it's recommended to improve clay soil is by digging in organic matter, eg compost, manure, coir etc.
We're on heavy clay, but we're quite lucky to be on a slight incline. We started improving the soil using bags of manure and soil improver from the garden centre just over a year ago and are seeing a big difference in the quality of soil already.
You could always work with it and create a bog garden, plenty of wildflowers like marsh marigold enjoy damp conditions. What sort of wildlife are you hoping to attract? I found it so rewarding last year watching the bees, butterflies and hoverflies on our plants where before there had been gravel, grasses and paving.