The Department of Health describe long term condition as a condition that can not be cured but can be managed through medication and/or therapy. Although there is no definitive list of these illnesses there are around 15 million people in England with at least one long term health problem.
Listed below are some internet sources that may be useful:
ATRIAL FIBRILLATION: www.afa.org.uk
HEART FAILURE: www.bhf.org.uk
CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD): http://www.blf.org.uk/ or you can use www.patient.co.uk and type in the health condition that you would like information about.