Sorry I was not able to talk to you about flowers this weekend. It is difficult to suggest anything without seeing your plot, but selecting flowers from an easily available Dr D.G. Hessayon's "Flower Expert" book would be a good place to start. Try planting some herbaceous perennials (their foliage dies back in the autumn and grows back in the spring). Plant in a circle, in odd numbers so that they look more natural and less square, with the tallest plants in the middle. Try matching and contrasting the colours and have at least one species in flower throughout the growing season. Roukenglen Garden Centre should have a wider selection than Homebase, B&Q or the supermarkets. Anything else could be found in the classified ads at the back of gardening magazines like Gardeners' World. They usually have special offers for matching plants.
If you just want to grow annuals sow a wild flower mix on a depleted soil.
Let me know if any of this is of any use or if I am teaching my granny to suck eggs again.