Ladbrokes will normally administer withdrawal requests if not instantly then within 24 hours.
Any additional time it takes to receive your money will depend on the agent dealing with it. By agent I mean if you are using an online payment provider like Paypal, or traditional banking methods.
E-Wallet solutions are always much faster and often on the same day, whilst card withdrawals can between 3-5 working days for funds to arrive back with you.
For more details on Ladbrokes banking methods, take a look at the section toward the top of this Ladbrokes review.