As a client of Consonance you may be storing your contacts’ personal information. If you are based in the UK, it is very likely that you should have to register with the ICO: Information Commissioner’s Office:
The UK’s independent authority set up to uphold information rights in the public interest, promoting openness by public bodies and data privacy for individuals.
Please visit their site here to read their advice and to register if necessary. They have a questionnaire that you can take which tells you whether you need to register with them.