For the formatting you can try this,

Use the case to get the correct character in front (or an empty string), and then add the incident_ref in 5 digits. (include leading zero's if needed)

CASE Event_Type

WHEN 'c' THEN 'R'

WHEN 'i' THEN''

ELSE 'P'

END + RIGHT('00000' + CAST(incident_ref As nvarchar(5) ), 5)

Louis