drainage in my garden? i cant put a land drain in.

Hydrangeas drink loads and are really easy to grow. (I use them for a drainage purpose too).

Evergreens are good because they have to keep drinking through the winter aswell to stop their leaves drying in the harsh winds. Viburnum tinus would be good.

trees will soak up water, a mature oak tree will drink 50 gallons of water per day

willow trees,or look for plants that like bog gardens