Gill Watson?
Mary Robins- very highly recommend. In Butlers Cross, so very close to Chesham.
Susie Pilbeam? An eventer really but very good.
Joss gray- again, an eventer but found his flat work advice second to none.
I use Louise Spate - she is at Chalfont & will travel although her yard is magnificent. She is really understanding and explains everything really well. PM if you want details