Ajuga reptans, Campanula muralis (often sold as C. portenschlagiana) and if it gets half a day's sun, Oreganum aureum

Definitely agree with Bamboo on Ajuga Reptens. It's one of the few plants I inherited when I moved here 15 years ago, never came across it until then. The blue flowers are very sweet and flower about now. RHS plant selector is free and easy to use - it's a bit like shopping online where you indicate your garden conditions and what you want from the plant. See http://apps.rhs.org.uk/plantselector (RHS site has been very helpful for me so far and saved me loads of money as I check out what I see in the plant catalogues using their search by name tab as well - http://apps.rhs.org.uk/plantselector/plantnamesearch) Happy hunting :-)

Vinca major, too, but it can become a garden thug in the UK.

Lamium maculatum 'beacon silver' dead nettle, will grow under tree canopies in poor soil conditions.

I second Vinca Major.

Somewhat invasive, but as it's so beautiful I can forgive it.

Another favourite of mine are yellow horned poppies - a prolific self seeder though.

I absolutely do not recommend Vinca major or minor - poor groundcover without its being chopped back to a couple of inches at least once a year, and even then it doesn't exactly cover the ground, just chucks out long runners everywhere, leaving plenty of space for weeds to grow inbetween.
The Lamium mentioned by 2ndhand though, yes, that's a good one, along with Lamium 'White Nancy'.

thank you gor your replies, think i might find this this a real help