The minimum top-up amount is 1 GBP and the minimum withdrawal amount is 0.01 GBP.
To link your bank account to the Shares application:
Access your Investing tab by clicking on the very left icon out of the four you can see at the bottom of the page.
Choose “Available to invest”.
Click under Linked bank account on the "Connect a bank account" to connect your bank account to Shares.
You can make a withdrawal as long as the cash is under withdrawable cash. You can check this in the Account section of your profile.
If the cash is still unsettled after selling shares, you need to wait 2 working days after the trade date for it to become withdrawable. After withdrawing the amount of your choice, you will get the cash in your linked bank account in 3-4 working days.