You can talk to your current bank as most high street banks offer the opportunity to set up a basic current account to fulfil this purpose. You cannot put any other funds into this account unless there is other funding perhaps and this has been pre-agreed with your local authority. 

The cash payments from your local authority could be made weekly, fortnightly, four weekly, monthly, or otherwise. You should find out when direct payments are made into your nominated bank account so that you can effectively manage timely payments out to your PA(s).