I need a PC app developed, I have an MS access db that I wish to market

General information for the business: Filing deadline CRM type tool for Accountants
Description of every module: i have developed a database in Access that I use to for recordong my clients information (MS Outlook type tool), that I also use a tool to track what statutory filing is due and it is invaluable.

Having done some market research I want to develop it into stand alone software. This is potentially ongoing work but I need a working version in the first instance.
Description of requirements/functionality: Ideally I would like the software to be Desktop based, but with an mobile app option for the client to update details on the move.

There is a some functionality that I would like, such as sending email reminders, assigning work to colleagues, ideally I would like it to be able to auto update outlook calendar.
OS requirements: Windows
Extra notes: Once I have guaged the interest I will send screenshots of the software that I currently use.