It was not a really a "tabernacle". Tabernacle was a term generally applied disparagingly to Nonconformist churches made partly of corrugated iron. Could this be the church?
St, Michael's and All Angels, a chapel of ease to the parish church of St. Mary's, was consecrated 5th March 1902. A temporary iron nave has been attached, with accommodation for 425 worshippers. The site, including that of the old Ocklynge Mission room, was the gift of the Duke of Devonshire K.G. Kelly's Directory of Sussex, 1905
In the Kelly's Directory of Sussex, 1915 it just says of Hankham there is an iron church seating 120 persons.
Stan