Hi Duncan
The Chilterns are an excellent area for Red Kites with easy viewing from the M40 .... as a passenger of course
.
I am not aware of any feeding stations but I do vaguely recollect reading somewhere on the Internet that one of the pubs in Watlington did feed the Red Kites.
Sorry, I have no further information .... I guess you will have to do a bit of research and visit all the pubs
.
Richard