How much are you after and what for?
If you just want a couple or three reasonably sized flakes for flint-and-steel sparks then I could put some into the post for you; I pass a field on my way into my usual place of work that is littered with flint nodules of all shapes, sizes and colours.
PM me with your address if that's what you want, but you may have to wait for a couple of weeks for me to come good on this, as I have some heavy off-site work commitments this next week and the Woodsmoke Woodlander course the week after.