Makers of cider for sale whose production, including that for their own consumption, does not exceed 70 hectolitres in any rolling period of twelve consecutive months, are exempt from the requirement to register as a maker of cider for sale. This means that they do not have to pay duty on the cider, providing their total production does not exceed 70 hectolitres.
The relevant legislation is section 62(3) of ALDA and the Cider and Perry (Exemption from Registration) Order 1976. Further information can be found in section 3 of Notice 162 (GOV.UK).
Anyone who makes cider purely for their own consumption (not for sale) does not need to be registered or pay duty.