Work will begin in August at the nursery near Princes Risborough in Buckinghamshire that sits in the green belt and an area of outstanding natural beauty.
The tea shop will seat 25 with a terrace area offering space for another 30 customers. There will also be a free Wi-Fi facility.
Both the farm shop and tea shop will concentrate on using locally-sourced produce and will be open every day all year round. Owners Simon and Alison Cheetham said: "This addition will really put us on the map."
They added: "There is a real need for a facility like this and we are determined to create a top-quality tea- shop and farm shop offering our current and new customers a fantastic outlet." The facility is set to open in March next year.