The APR you will be charged on cash withdrawals is more often than not twice as much as that charged on purchases.
Typical APRs for cash withdrawals range from around 25% to 30% and this level of interest is charged on the balance from the day it is withdrawn until it is repaid in full.
Most credit card providers do not offer a 56 day interest-free period on cash advances and any promotional interest-free period on purchases will not apply to cash withdrawals.