MYSQL Database with Web Interface

SQL (preferably) MySQL database(s) with a web interface.
Initial phase up to 50 simultaneous online users to access data which will be held with our ISP. Final phase will be several hundred users and very secure.
This project is for a prototype with just three users for proof of concept and testing so full security does not need to be implemented. But you will have to demonstrate that it can be.
Three levels of user (A , Band C) with password access to predetermined tables and reports. levels shown at each data type below
Data stored:
1. Customer contact and project status data - A&B
2. Customer Contract, project documents and billing data - A and some B (the particular customer managers and implementers)
3. Employees CV (excluding personal identity) and skills matrix. - A&B plus anyone on web site who registers with full details.
4. Full employee data including salary etc - A only
5. Responses from web site to integrate with 1. - A&B
6. Knowledge base A&B
7. Shared Diary system preferably able to sync to users Outlook or other email clents
Level C will be partial access (e.g. read only) to some yet to be specified sub-set of the above
Please quote price and time scale to deliver a prototype to enable full requirement and specification to be developed.
Successful developer of prototype will get the implementation project as well as ongoing enhancements and support contract.
Developer MUST live within easy commute to Oxford - pleae don't try and persuade us otherwise - you will simply waste your time and ours.