All research projects using personal data must be registered with Legal Services before the data is collected. This includes projects approved by the Joint Research Office. Form 2 should be used to register most projects. For those approved by the Joint Research Office Form 9 should be used. Both forms can be downloaded from https://www.ucl.ac.uk/legal-services/data-protection-overview. They should be completed electronically and sent to firstname.lastname@example.org with copies of any information sheets and consent forms that you are using.
Projects using truly anonymised or aggregated information does not have to be registered with Legal Services and you do not have to worry about compliance with the Data Protection Act 1998.