Here is my path through the online tool.
Do I have to tell the Information Commissioner about the information my business processes?
Q1. Are you processing personal information? Yes
Q2. Do you process the information on a computer or on any system that can process information automatically? Yes
Q3. Are you, or is your business, a data controller? Yes
Q4. Are you processing data for any of the purposes listed below? No
Q5. Are you only processing personal data for personal, family, household or recreational reasons? No
Q6. Are you only processing personal data to maintain a public register? No
Q7. Is your business a not-for-profit organisation? No
Q8. Do you only process data for staff administration, advertising, marketing, public relations, or accounts and records? Yes
Q9. Do you process individuals' information for staff administration? No
Q10. Do you process individuals' information for advertising, marketing or public relations? Yes
Q11. Does your business comply with the rules allowing exemption from notification on advertising, marketing and public relations grounds? Yes
Q12. Do you process individuals' information for accounts or financial records? Yes
Q13. Does your business comply with the rules allowing exemption from notification on accounts and financial records grounds? Yes
Q14. Does your business only process data for the purpose of judicial functions? No
Conclusion
You do not have to notify the Information Commissioner, although it's important that your business adheres to the eight principles of the Data Protection Act 1998 and understands best practice for managing information.
Some of your answers may be different. When you obtain personal data from a customer you should also get their permission to allow the data to be shared with MCS/REAL.