I've been looking into the same thing just today and I'm not liking the fees for business bank accounts
The client I already have is just paying into my private account (we have a very informal arrangement and don't have a contract or anything), but I'm thinking that that it will appear more professional to have a business account for new clients as I find them.
Another thing, my husband and I have started the business as a partnership, except he hasn't left his FT employment yet. Again, the clients he will have will most likely expect to be paying invoices to a business bank account, rather than his personal one.