LONDON, Nov. 12 (AP)—A government spokesman declared today Britain would adhere to her original decision not to delay her withdrawal from Palestine indefinitely nor be responsible for single-handed implementation of any partition settlement over a long period. This source disclosed that top British policy-makers had drawn up three provisional time tables for the evacuation of British troops and civil administrators from the Holy Land prior to March, 1949. The schedules are to be submitted to the Cabinet for consideration tomorrow.