I've just had the kitchen skimmed, so a reasonable surface for tiles. My
past efforts have been pretty poor though - just looks like it's been
done by somebody not very good at tiling. I don't seem to have the
eye/hand for it.

Might these be a better bet:

http://www.wickes.co.uk/decorative-t...t/mosiactiles/

--
Cheers, Rob