You need sufficient cleared funds, and withdrawal payments can only be made in the name of and to the registered account holder. That rules out directing a withdrawal to someone else. Accounts in Great Britain use GBP.
For most payment types, the withdrawal route is through your account settings:
Withdrawal requests remain subject to the terms allowing bet365 to withhold funds. Having a balance is therefore not the only condition for making a withdrawal.
Authorised withdrawals usually return to the payment method used for the deposit. If you funded the balance through more than one method, the withdrawal is split proportionally between those methods; you should expect the return to follow how the balance was funded.
bet365 does not impose a maximum withdrawal amount per day, but individual payment methods have maximum per-transaction limits. Check the limit for your method when deciding the size of a request.