Kaffarah is a form of levy payable if you intentionally break or miss a fast during the month of Ramadan. Should you have a legitimate and unavoidable reason for doing so, it is highly likely this will fall into the Fidyah category nevertheless. The forfeit entails either feeding a total of 60 people in need or continuously fasting for 60 days for each fast missed or broken.
To make up for the missed or broken fast, you must fast continuously for 60 days, or feed 60 poor people. The total amount for each missed or broken fast would be £240. You may pay your Kaffarah through this page and HRF will use it to serve the needy this Ramadan on your behalf.
So, to conclude, Zakat, Fidyah and Kaffarah are all deemed obligatory, whereas Sadaqah (charity) is a selfless and humble act of sincerity which is carried out without being obligated to do so.