What sort of flowers/shrubs thrive best in this soil?

Eventually we have found out that the type of soil around us is clay, with a subsoil of Keuper Marl mainly used for growing crops of wheat, beans and fruit and a few hops. we will probably chuck a thin layer of compost on top during the winter months for it to settle into the soil to help with fertilisation.
In preparation for next year we would like to plant one or two flowers or shrubs that wil flower in the winter months. Then we would like a mixture of different flowers that flower at different times from spring through to autumn.
Our garden is not massive so we can't have large shrubs and definitley no vines.
Is there a website where you can find out about the different flowering times etc? Thanks.

 

Have a look over this site...http://www.findmeplants.co.uk/default.aspx

Steve...

 

Glad I am not the only one up early. Thanks for the link.