Inhouse Database Integration

I am currently working as a contractor within a large financial services organisation. The requirements : We need to integrate their business website with their inhouse database, this means clients/customers can login through the website and retrieve account details/balance/pay debts and so forth. This is a large firm, with over 400 permanant staff thus the candidate must be highly experienced in integrating with such systems. The website design & build will be handled solely by me. The job of the candidate is to take the website, integrate this with the database inhouse within my clients firm, and ensure everything runs securely online so customers have an easy means of logging in and retrieving their account details & paying bills. The successful candidate must be able to commute or be based in or around Leeds, my client is based just outside leeds city centre & thus with this type of work i believe it to be benficial if the client could come in and work with me to roll out this project to the highest standards. Please reply in the first instance with previous such experience, a rough estimate & quotation based on the above, and a timescale for integration.