From cash machines (ATMs):
As long as you have enough in your account, you can withdraw up to £500 in any one day with a FlexAccount.
From over the counter in branch:
You can withdraw up to £500 a day at your local branch, as long as you have the funds available in your account including within an arranged overdraft limit. If you need more than £500, please give your branch at least 2 full working days' notice. (Some requests may take up to three full working days – so we recommend checking with your branch beforehand.) For cash withdrawals over £500, you will need to present one piece of ID – either your passport or driving licence (with the paper counterpart copy).
From a Post Office:
You can withdraw up to £500 in cash at any Post Office branch using your card and PIN.