Clearly it is beyond the scope of these pages to answer every question relating to medical conditions and gaining a PPL or NPPL. The Civil Aviation Authority (CAA) Medical Department website (http://www.caa.co.uk/default.aspx?catid=49 ) is very helpful, and contains a lot of information, FAQs, contacts and links to relevant sources.
Some symptoms are common across a range of conditions - continence issues and fatigue, for example. The effective management of these, and side effects of any medication used for symptomatic relief, can be a key factor in the enjoyment of a trial lesson.
Some of the more common aviator disabilities, and their implications for flight, are briefly detailed here...